Do Earthworms Glow in the Dark?

Why, yes. There are some that do glow softly. Earthworms secrete a slimy fluid that they use for locomotion, among other things. This coelomic fluid, in certain species, gives off a distinct blue or orange glow.

To find out more than you ever wanted to know about glow-in-the-dark worms, check out:

Earthworm Bioluminescence