Grinder

Grinders are metal discs found in some Fortresses and Castles of Super Mario World. There are two types of Grinders, line-guided and non-line-guided. The line-guided variety travels along a dotted line while non line-guided Grinders travel across the floor. The blades are rather large and cannot be jumped on, although they can be defeated by a Slope Slide (which displays a glitchy sprite). Mario or Luigi can, however, Spin Jump onto them, which lets them bounce off the Grinder without taking any damage.

Grinders re-appeared in Yoshi's Story.

In Super Mario Galaxy 2, Grinders appeared in the Puzzle Plank Galaxy and the Rolling Masterpiece Galaxy, where they would cut through planks of wood and cause them to fall. When Mario goes on a certain part of the planet or passes the Grinder, it starts moving, and any enemy that touches it disappears.