So I took a small rock from Vojak peak of Ucka (Uchka) mountain in Croatia. Later I noticed interesting (well, it's interesting to me, since I know close to nothing about fossils) shape on it.
I wonder is it a fossil at all and if it is, what was it fossilized there?
The rock is limestone:
http://www.pp-ucka.hr/en/natural-heritage/geology/
I would appreciate your help in identifying it.