Yum-Yum

A Yum-yum is a googly-eyed clam that bounces around Treasure Trove Cove. If it hits Banjo and Kazooie, not only will it injure the pair, but it will also cause the bear and bird to drop a Red Feather and an Egg, which Yum-yum will proceed to gobble up if not picked back up quickly.

Yum-yums can also be found 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.

Trivia

 * Getting bit by a Yum Yum in Grunty's Revenge is the only way to get a feather, gold feather, or egg without a nest.