So I have a plane as my floor with a collision tag
Several Spheres using Mograph and a Rigid tag so they interact with one another
A animated sphere with an Attractor tag so all the other spheres follow it around the scene.
What I'm trying to achieve though is when the spheres collide with the floor (sand texture) they make a trail. Currently they make an indentation (which is good) but once they move, there are no physical trails, just indents that follow the sphere around.
1. Add a Plane object underneath your sand plane and offset it on negative Y but, not beyond the depth of your spheres so they still show.
2. Apply a Static Rigid Body tag to this new plane and remove it from your sand plane if there is one, and make sure the Collision Deformer is applied to your sand plane. Collision Deformer will do the work.
3. The sand plane will need 100-200 (maybe more) subdivisions to look convincing but you can cache the result in the Collision Deformer.
4. In the Collision Deformer Object tab set the Falloff to Surface (Collider is best but much slower at computing result) and Restore Shape to 0% (Play with this for the effect you want).
5. On the Collider tab set it to Outside (worked for me, again play with the options).
Your spheres should now leave trails as they roll about :)