Is there such a thing as a truly rigid body? If so, give an example. If not, explain why.

A rigid body is the on which shows no deformation as the time progresses that is the distance between any two particles of the body remains constant as the time progresses. One can see this from the fact that no two particles of a body experience exactly the same amount of forces. This effect can be seen in situations where the center of gravity of the object is not at the same point as the center of mass.
The shift in the center of gravity of the object is caused because the acceleration due to gravity for the particle at the top is relatively smaller than the particle at the bottom. However, this amount is very small and can be approximated.