Zider

Ziders are small wormlike creatures that slide along the slimy external membrane of the Single-cell Mountain. They move using their array of flagella to drag themselves along.

They have basic light sensors that allow them to tell when something is looming over them, but nothing more. When they sense something above them, they start a chemical reaction inside their bodies that releases a threatening chemical hiss.

They are harmless, relying on their hiss to drive away predators.