Yum-Yum

A Yum-yum is a googly-eyed clam which bounces around Treasure Trove Cove. If it hits Banjo, not only will it injure him, but cause him to drop a Red Feather and an Egg which Yum-yum will quickly gobble up if they're not picked back up.

Yum-yums can also be seen in Banjo-Kazooie: Grunty's Revenge where they populate Breegull Beach and Spiller's Harbor. They behave identically, but will also eat Golden Feathers in addition to other consumables.