Tiki Zing (Factory)
From the Super Mario Wiki
Tiki Zings are Factory enemies in Donkey Kong Country Returns and Donkey Kong Country Returns 3D. They resemble circular saws with a mischievous grin. They only appear in the level Foggy Fumes, and are similar to their namesake and Buzzbites.
Tiki Zings are usually found circuiting around half-exposed platforms, but they can also spawn from pipes on the ceiling and start rolling to the right once they hit the ground. They are completely invincible, but the Kongs can simply jump over them to avoid them.