Flotsam

Flotsam is an enemy from Rusty Bucket Bay in Banjo-Kazooie. It hangs on the walls of The Rusty Bucket and disguises itself as a flotation ring, springing to life if Banjo and Kazooie get too close and bouncing after them.

Although its bright colors make it relatively easy to spot, it can be hard to avoid if you round a corner and one happens to be there. Interesting enough, this enemy is immune to the Beak Bomb ability.

The best way to deal with them is simply attacking them with a well-timed Rat-a-tat Rap. When defeated, the Floatsam will comically deflate before vanishing.

Etymology
In real life, "flotsam" is a term used for goods floating in the sea after a ship sinking, while Flotsam is the name of a character in the Disney film The Little Mermaid, and a Manta Ray enemy in Donkey Kong Country 2: Diddy's Kong Quest.