Clinker

Clinkers are large, brown, amoeba-like creatures of questionable composition that block the ventilation grates in Clinker's Cavern of Grunty Industries. Banjo and Kazooie are tasked with clearing twenty of them out in a limited amount of time before the area becomes toxic. (Clinkers can still be cleared after the air is infected but it is a risky and dangerous maneuver.)

If Banjo inputs the cheat "HONEYKING" in the Code Chamber of Mayahem Temple, the Clinkers cannot harm him even after the timer has expired; he will just have to deal with the toxic, greenish gas.

Trivia
The Clinkers are named after the British slang term "clinker", which is a deposit of rust and grime that tends to form on various metallic surfaces. However, it is unknown if the Clinkers in Banjo-Tooie are comprised of said material or not.