Fish?

Fish?

Observation - Fish? - UK and Ireland. Description: Apologies for the awful and also gruesome picture, but I saw this last year in a rockpool and no-one has been able to identify this carcass for me. The head was large, I'd say around a foot give or take and I'm very curious to know what it could be.

Apologies for the awful and also gruesome picture, but I saw this last year in a rockpool and no-one has been able to identify this carcass for me.
The head was large, I'd say around a foot give or take and I'm very curious to know what it could be.