Simply rock or leaf?

[amon81]

Hi, i don't know id it's only a rock or a leaf. Someone have one idea. Found by my son on river of the Ionian Sea in the Mediterranean, south of Italy.. maybe it's only a suggestion.. every opinion is appreciated.. thanks

 

[Pemphix]

In my opinion it's no leaf, just dendrites of iron/mangan.

But more info about locality/geology would be helpful - southern italy is big

[Fossildude19]

Not a leaf.

I agree, looks like dendritic iron/manganese with conchoidal fractures in the rock. 

Regards,

[TqB]

I agree, hackle fracture.