What is this?

[Fossilywend]

Hi everyone. This is my first request for an ID, I'm a complete newbie with limited knowledge but very eager to learn. This might be nothing, but I thought it was strange. Found loose on a Yorkshire beach (UK)  unsure whether it was washed up by the sea or came away in a cliff fall. Area known for ammonites/Mesazoic/Jurassic finds. Measures approx 9cm in length, 18 cm circumference.     

[ynot]

Not seeing a fossil in this one, maybe a piece of chert/flint.

 

Welcome to TFF!

[TqB]

Looks like a limestone concretion with a thick pyrite skin, common at some levels (especially the Jet Rock). May or may not contain fossils, usually ammonites but more exotic things sometimes occur.

 

Pyrite shards from these are dangerously sharp so wear goggles and gloves when hitting!