Unity3D colliders act more like sponges than solid objects

Question

I make a platformer in Unity3D, and I noticed that Unity3D colliders behave strangely in the simple sense that they don't seem durable.

To better demonstrate the problem, I used a simple sphere and a cube and paused the game, because the sphere “jumps”. By flipping frames in the frame, you can clearly see the ball falling below the cube.

Why is this happening and how can I fix it?

Answer 1

. , , . , . .

1. Discrete - unless you experience problems you should use discrete. 
2. Continuous - for fast moving objects that are interacting with static geometry.
3. Continuous Dynamic -as above but are also interacting with other fast moving dynamic objects.

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