I am not sure what this is.

[Neogeo]

I found this a while back,and just re-found...Ant thoughts... Fossil
The inside is some type of crystal.

 

[Tylocidaris]

Hey Neogeo, you've found a partial fossil echinoid spine. The calcite that replaced the original material is probably very reflective on the broken ends. That's a pretty big one and worth keeping.

 

[Neogeo]

Cool I never thought of that...But makes sence,they come in many sizes & shapes...Thanx.