I have got a scene with some cloned pebbles and a floor. My pebbles have a rigid body tag and my floor has a collider tag. When I hit play my pebbles fall onto the floor. Perfect. But the problem is they just keep rolling and bouncing around for ages and never settle. I have added an extra 200 frames to the start of my scene to let them settle before the action starts. But this doesn't work. they just keep moving around.