Tiki Zing (Factory)
From the Super Mario Wiki
Tiki Zings are enemies in Donkey Kong Country Returns and Donkey Kong Country Returns 3D. Tiki Zings appear to be circular saws with a mischievous grin, and are similar to their namesake and Buzzbites. They only appear in one level, Foggy Fumes of the Factory world; due to it being a silhouette level, Tiki Zings are never shown entirely.
Tiki Zings are usually found circuiting around partially exposed platforms rapidly, but some of them fall from the ceiling either through an opening or from a pipe. Once it hits the platform, the Tiki Zing starts rolling around the platform. They are invincible and cannot be defeated, and the Kongs should only avoid any Tiki Zings they come across.