This pathological ammonite of the species Amaltheus gibbosus shows a some interesting injury’s of the both sides of the shell. A Possibile predator would be a Crustacean.
The shape of the penetration marks that the counter point for the claw was might the entranced of the living chamber or (or also) the Keel. Also the Beak like mouthparts of a Squid would be able to do comparable damage.
Ammonite shells with predation marks are quite common but in the most cases they are found as fragments that are not any more able to tell a story. Pieces like this are more unlikely.

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