These clams kept despawning on me and I have no idea why that would be part of Vanilla (I searched for clam bait and didn’t see any posts about it either discussing it).
I swam to tons of them only for them to despawn in front of me or even when I’m trying to open. People are definitely not sniping them in front of me or anything. When the first one did (it despawned while I fought on top of it) that I looked around trying to figure out who took it, but as I kept playing I kept watching them just randomly despawn.