What to call an Object that falls only when it's collided with? I am currently working on Objects Blocks for my 2D Jump'n'Run. Now I want to add a new type of block, which falls down only if the player an actor collides with it. But I don't know what to call this type. Or more generally Objects that only do stuff change behaviour if interacted with. How should I name the first type and the second more general type?