forioscribe

It's a centipede, but I don't know what sort.

This one curls up into a ball. I found it in a spider web underneath an air conditioner. It was still alive when I flushed it down the toilet.

Ah! If you'd said it curled into a ball, I'd have said "millipede" immediately. Centipedes don't normally do that.

They're quite harmless. There's no need to kill them unless you get an invasion in the house. Centipedes, on the other hand, can give you quite a nasty bite.

Ah, Googling "tiny centipede" got me this:

Millipedes
Dark brown to black worm-like insects that curl into a little "swirl" shape when they die and are commonly found in basements, garages, or slab level homes. They tend to be found near doors and windows but not exclusively.

Millipedes spend most of their life living next and underneath of your home and only come inside in response to negative exterior stimuli. These stimuli are rapid or prolonged rain, overpopulation, or sudden temperature drops.

Control consists of comprehensive exterior application that focuses on treating under all moveable items in areas against homes like slates, slabs, rocks, splash plates, birdbaths, mulch bags, and anything that sits directly on the soil for protracted periods. This coupled with an interior application in basement, garage, and any interior slab level areas will reduce your population and regular quarterly exterior treatment will keep new populations from building up adjacent to the home.

millipede! used to see them creeping across my bedroom ceiling when i was little. eeww.

The few I've seen here are on the floor. Much easier to get to them for disposal.