Is this a battle prize? If so, could you tell me who my pet needs to fight? TIA

I think it's an unreleased challenger, or it's loot for a previously released challenger that we are not able to battle yet. It may be related to Fishing. As far as I know, nothing official has been posted about those new items in the directory.

Thank you. I really want to nab it for food for one of my pets. I'm pretty near the top and I want to stay there.