We believe the brown worm our reader found in his toilet is an earthworm. Earthworms aren’t known to carry or transmit any human diseases, so they are generally considered to be harmless!

We think the creature our reader found in her toilet could be either a bloodworm or an earthworm. It is also possible that it is a different species entirely, but these are two of the most common worms found in toilets, and they share some resemblance to the organism our reader found.