Hi OP, I thought would be a great question for the newly created Geology group, so I posted a link to it there and got this great answer – in short:

There are many small fossils on that rock. It would be hard to tell what the rock itself is from just the photo. Limestone is the most likely candidate.

Go and read the full answer for more details!

If you’re happy with the answers you’ve got could you edit your title to add [SOLVED] at the end? Thanks, Michael

Yeah. Looks like some sedimentary rock that has a few shells fossilized. If I had to bet, the rock itself is limestone perhaps?