What is it Corprolite or Petrified Wood?

[3rdGn]

My grandpa use to help me identify my finds this and my previous post shows the two we were working on identifying when he died in July. I thought I should continue what we started. The first he thought was a diamond based on our tests. He thought this (shown in attachment) was corprolite because of the exterior. The interior has greenish and yellowish grass or plant fiber like strands, red globular in brown and blue stone.