diff --git a/README.md b/README.md
index a67a7ad..0b1a2e8 100644
--- a/README.md
+++ b/README.md
@@ -47,7 +47,7 @@ A `Grid` stores its locations by value in a `std::vector<Location>`. `Grid::getL
 
 ## Grid Layout and Movement
 
-`Environment(id, name, size)` creates a square grid of `size` × `size` locations. The grid is given the environment's own `id`, and each location's id has the form `<gridId>-<x>-<y>` (for example `0-2-1`). Locations are generated row by row, with `x` and `y` each running from `0` to `size - 1`; `Grid::getLocations()` and `Environment::printConsoleRepresentation()` follow that order.
+`Environment(id, name, size)` creates a square grid of `size` × `size` locations. The grid is given the environment's own `id`, and each location's id has the form `<gridId>-<x>-<y>` (for example `0-2-1`). Locations are generated row by row, with `x` and `y` each running from `0` to `size - 1`; `Grid::getLocations()` and `Environment::printConsoleRepresentation()` follow that order, and `Environment::getFirstEntity` returns the first entity of the first occupied location in that order, regardless of the order in which entities were added. `printConsoleRepresentation()` prints each location as `[x] ` when it is occupied or `[ ] ` when it is empty.
 
 `Environment::addEntity` (and `Grid::addEntity`) places the entity in a location chosen by `Grid::getRandomLocation()`, not in the first location. To place an entity at a specific location, use `addEntityToLocation`.
 
@@ -59,7 +59,7 @@ A `Grid` stores its locations by value in a `std::vector<Location>`. `Grid::getL
 
 ## Entity Identity
 
-Entities are matched by `Entity::getId()`, not by address. `Location::isEntityPresent`, `Location::removeEntity`, and `Environment::getEntity` all compare ids, so two distinct `Entity` objects that share an id are treated as the same entity. Entity ids should therefore be unique within an environment.
+Entities are matched by `Entity::getId()`, not by address. `Location::isEntityPresent`, `Location::removeEntity`, and `Environment::getEntity` all compare ids, so two distinct `Entity` objects that share an id are treated as the same entity. Removing through such a twin takes the stored entity out of its location but resets only the twin's ids, so the stored entity keeps ids describing a placement it no longer has. Entity ids should therefore be unique within an environment.
 
 A newly constructed entity has an environment id and grid id of `-1` and a location id of `"N/S"`. Placing it through an `Environment` sets all three; `Environment::removeEntity` resets them to those same values.
 
@@ -67,6 +67,8 @@ A newly constructed entity has an environment id and grid id of `-1` and a locat
 
 Adding is likewise unchecked. `addEntity` and `addEntityToLocation` do not test whether the entity is already present, so adding it a second time stores a second pointer to it (in another location, or in the same one), its location id names only the most recent location, and `getNumEntities` counts it twice. To relocate an entity that is already placed, use `moveEntityToNewLocation` or one of the directional move methods, which remove it before adding it again.
 
+Removal takes out at most one pointer per location. An entity added to two different locations is removed from both, but one added twice to the same location keeps a pointer there after `removeEntity`: it is still present and still counted, while its ids have already been reset, so a directional move then throws `std::runtime_error` because its location id `"N/S"` names no location.
+
 `Grid::removeLocation` also detaches any entities in the removed location: it resets their location id to `"N/S"` and their grid id to `-1`. It leaves their environment id unchanged, since the grid has no knowledge of its environment.
 
 ## Errors
diff --git a/src/tests.cpp b/src/tests.cpp
index b861946..8d1ca2d 100644
--- a/src/tests.cpp
+++ b/src/tests.cpp
@@ -1004,6 +1004,141 @@ void testAddingEntityTwiceStoresItTwice() {
     std::cout << " --- " << "Success" << std::endl;
 }
 
+std::string captureConsoleRepresentation(Environment& environment) {
+    std::ostringstream buffer;
+    std::streambuf* previousBuffer = std::cout.rdbuf(buffer.rdbuf());
+    environment.printConsoleRepresentation();
+    std::cout.rdbuf(previousBuffer);
+    return buffer.str();
+}
+
+void testPrintingConsoleRepresentationRowByRow() {
+    std::cout << "Test 60 - Printing the console representation row by row";
+    Environment environment(0, "Earth", 2);
+    assert(captureConsoleRepresentation(environment) == "[ ] [ ] \n[ ] [ ] \n\n");
+    Entity entity(0, "Daniel");
+    environment.addEntityToLocation(entity, environment.getGrid()->getLocationByCoordinates(1, 0));
+    assert(captureConsoleRepresentation(environment) == "[ ] [x] \n[ ] [ ] \n\n");
+    environment.moveEntityDown(0);
+    assert(captureConsoleRepresentation(environment) == "[ ] [ ] \n[ ] [x] \n\n");
+    std::cout << " --- " << "Success" << std::endl;
+}
+
+void testPrintingConsoleRepresentationMisalignsAfterSettingGridSize() {
+    std::cout << "Test 61 - Printing the console representation misaligns after setting the grid size";
+    Environment environment(0, "Earth", 2);
+    environment.getGrid()->setSize(3);
+    assert(captureConsoleRepresentation(environment) == "[ ] [ ] [ ] \n[ ] \n");
+    std::cout << " --- " << "Success" << std::endl;
+}
+
+void testRetrievingFirstEntityFollowsLocationOrder() {
+    std::cout << "Test 62 - Retrieving the first entity follows location order, not insertion order";
+    Environment environment(0, "Earth", 2);
+    Entity addedFirst(1, "Daniel");
+    Entity addedSecond(2, "Bob");
+    environment.addEntityToLocation(addedFirst, environment.getGrid()->getLocationByCoordinates(0, 1));
+    environment.addEntityToLocation(addedSecond, environment.getGrid()->getLocationByCoordinates(1, 0));
+    assert(&environment.getFirstEntity() == &addedSecond);
+    std::cout << " --- " << "Success" << std::endl;
+}
+
+void testRemovingLocationLeavesEntityEnvironmentIdUnchanged() {
+    std::cout << "Test 63 - Removing a location leaves the environment id of its entities unchanged";
+    Environment environment(5, "Earth", 2);
+    Entity entity(0, "Daniel");
+    Location& location = environment.getGrid()->getLocationByCoordinates(0, 0);
+    environment.addEntityToLocation(entity, location);
+    environment.getGrid()->removeLocation(location);
+    assert(entity.getEnvironmentId() == 5);
+    assert(entity.getGridId() == -1);
+    assert(entity.getLocationId() == "N/S");
+    assert(environment.isEntityPresent(entity) == false);
+    assert(environment.getNumEntities() == 0);
+    std::cout << " --- " << "Success" << std::endl;
+}
+
+void testAddingLocationToGridStoresACopy() {
+    std::cout << "Test 64 - Adding a location to a grid stores a copy of it";
+    Grid grid(0, 2);
+    Location original("extra-location", 10, 10);
+    grid.addLocation(original);
+    Entity entity(0, "Daniel");
+    original.addEntity(&entity);
+    assert(original.getNumEntities() == 1);
+    assert(grid.getLocation("extra-location").getNumEntities() == 0);
+    assert(grid.isEntityPresent(entity) == false);
+    std::cout << " --- " << "Success" << std::endl;
+}
+
+void testMovingEntityInSingleLocationGridAlwaysReturnsFalse() {
+    std::cout << "Test 65 - Moving an entity in a single-location grid always returns false";
+    Environment environment(0, "Earth", 1);
+    Entity entity(0, "Daniel");
+    environment.addEntity(entity);
+    assert(entity.getLocationId() == "0-0-0");
+    assert(environment.moveEntityUp(0) == false);
+    assert(environment.moveEntityRight(0) == false);
+    assert(environment.moveEntityDown(0) == false);
+    assert(environment.moveEntityLeft(0) == false);
+    for (size_t i = 0; i < 20; i++) {
+        assert(environment.moveEntityToRandomAdjacentLocation(0) == false);
+    }
+    assert(entity.getLocationId() == "0-0-0");
+    assert(environment.getNumEntities() == 1);
+    std::cout << " --- " << "Success" << std::endl;
+}
+
+void testRemovingEntityAddedTwiceToOneLocationLeavesOnePointer() {
+    std::cout << "Test 66 - Removing an entity added twice to one location leaves one pointer behind";
+    Environment environment(0, "Earth", 2);
+    Entity entity(0, "Daniel");
+    Location& location = environment.getGrid()->getLocationByCoordinates(0, 0);
+    environment.addEntityToLocation(entity, location);
+    environment.addEntityToLocation(entity, location);
+    environment.removeEntity(entity);
+    assert(location.getNumEntities() == 1);
+    assert(environment.isEntityPresent(entity) == true);
+    assert(entity.getEnvironmentId() == -1);
+    assert(entity.getGridId() == -1);
+    assert(entity.getLocationId() == "N/S");
+    bool threw = false;
+    try {
+        environment.moveEntityUp(0);
+    } catch (const std::runtime_error& e) {
+        threw = true;
+    }
+    assert(threw == true);
+    std::cout << " --- " << "Success" << std::endl;
+}
+
+void testRemovingEntityAddedToTwoLocationsRemovesBoth() {
+    std::cout << "Test 67 - Removing an entity added to two locations removes it from both";
+    Environment environment(0, "Earth", 2);
+    Entity entity(0, "Daniel");
+    environment.addEntityToLocation(entity, environment.getGrid()->getLocationByCoordinates(0, 0));
+    environment.addEntityToLocation(entity, environment.getGrid()->getLocationByCoordinates(1, 1));
+    environment.removeEntity(entity);
+    assert(environment.isEntityPresent(entity) == false);
+    assert(environment.getNumEntities() == 0);
+    std::cout << " --- " << "Success" << std::endl;
+}
+
+void testRemovingEntityViaSameIdTwinLeavesOriginalIdsStale() {
+    std::cout << "Test 68 - Removing an entity via a same-id twin leaves the original's ids stale";
+    Environment environment(0, "Earth", 2);
+    Entity original(5, "Daniel");
+    Entity twin(5, "Bob");
+    environment.addEntityToLocation(original, environment.getGrid()->getLocationByCoordinates(1, 0));
+    environment.removeEntity(twin);
+    assert(environment.isEntityPresent(original) == false);
+    assert(environment.getNumEntities() == 0);
+    assert(original.getEnvironmentId() == 0);
+    assert(original.getGridId() == 0);
+    assert(original.getLocationId() == "0-1-0");
+    std::cout << " --- " << "Success" << std::endl;
+}
+
 void seedRandomNumberGenerator() {
     srand (time (NULL));
 }
@@ -1072,5 +1207,14 @@ int main() {
     testPlacingAndRemovingEntityResetsAllIds();
     testEntitiesSharingAnIdAreMatchedAsTheSameEntity();
     testAddingEntityTwiceStoresItTwice();
+    testPrintingConsoleRepresentationRowByRow();
+    testPrintingConsoleRepresentationMisalignsAfterSettingGridSize();
+    testRetrievingFirstEntityFollowsLocationOrder();
+    testRemovingLocationLeavesEntityEnvironmentIdUnchanged();
+    testAddingLocationToGridStoresACopy();
+    testMovingEntityInSingleLocationGridAlwaysReturnsFalse();
+    testRemovingEntityAddedTwiceToOneLocationLeavesOnePointer();
+    testRemovingEntityAddedToTwoLocationsRemovesBoth();
+    testRemovingEntityViaSameIdTwinLeavesOriginalIdsStale();
     return 0;
 }
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