Hi, it's my first post here. I found some fossils like this and asked about this on polish forum and i got help - it's a probably stromatoporoids. On one of them it's a something what looks like stalk. I don't know but probably is only core/internal layers (rest decay). It is possible that something gather inside (alga)? Found in southern Poland - Layer; middle or late jurrasic period. What do you think? (sorry for my english).