Klam
From the Super Mario Wiki
Klams are large, sinister-looking clams found in Donkey Kong 64.
Six Klams can be found in a locked chest in the area Gloomy Galleon. In order to get inside this chest and reach the Klams, Tiny Kong must shrink down in size using a Mini-Monkey Barrel and swim through the key hole on the chest's lock. Once inside, Tiny will find several Klams opening and closing their mouths in a repetitive fashion; inside the mouth of each Klam is a pearl.
Tiny must carefully swim inside a Klam and grab the pearl within. Only the Klam's teeth can injure the monkey. Once Tiny grabs all the pearls, she must return them to the Mermaid's seashell citadel where she can exchange them for a Golden Banana.

