Hello.
Today i found in the same area close to the beach in Greece 4 rocks.
Looks like agatized fossilized corals or sponge or something similar.
Maybe is only a strange rock.
This area in lost of time years have water very rich in silicon.
So, can anyone help for identification???
The rocks is very heavy.
I have a lot of photos but they need to put only one.
This one photo is a broken piece of the rock . It's little from outside and inside.
Thank you!!!