Why are my boxes being kneaded?

Unity Engine
1

Why are my boxes being kneaded and why do they get kind of squished when they should be as solid as rocks?

Video:

Here are the box settings:

Thanks in advance!

2

Try changing Default Contact Offset to a smaller value in the Physics settings. However you might find the boxes become unstable and jittery - physics simulations aren’t perfect and you might not be able to get them to stack perfectly, especially when you have more than 5 or so. Other solutions might be to lock objects in place once they have landed by setting rigidbody.isKinematic = false or using custom code to make them fall and without using physics.