Shururun

Shururun (シュルルン) is an enemy from Mega Man 8 and Mega Man & Bass that appears from pits like Up'n'Down, but faster, appearing in shorter intervals. It sports a structure similar to a spiked collar around it. Whenever Mega Man destroys one, another will appear momentarily after a few seconds. In Mega Man 8 they appear in Astro Man's stage, Grenade Man's stage, and the second Wily Tower stage. In Mega Man & Bass they appear in Astro Man's stage and King Stage 2.

In Mega Man & Bass, Astro Man uses a technique to create portals in the floor that have Shururuns.

Etymology
Its name may be derived from "shururu", a Japanese onomatopoeia for something doing a whirling or snaking motion.