Yes it is. And calcitized.

thank you Ramkumar 

I would agree it looks like a coral but I would need to see more pictures.

Thank you David 

I don't have more pictures

 Can it be attributed to the Miocene?

Apparently it (the circled one) DOES NOT look like a coral, from it's texture.

Do you have any thin sections made for this sample ?

Thank you Ramakrishna.

I dont have thin sections

Could you refer to Peter Scholle's AAPG Special Publication whic explicitly deals with Carbonates in thin section ? You can compare with coral samples. The bilateral symmetry in your "rock-butterfly" and its size suggests it may be - repeat may be- a cross section of a bivalve ??

Thank you dear colleague;

I think a croos section of rudist!!

Rudists, like corals, are colonial. Can it be so isolated and so 'lonely'?

Dear colleague,

this picture shows the base of the bar in question