Bloodworm

From Memory Alpha, the free Star Trek reference.

You may also be looking for Regulan bloodworms.

Bloodworms were an animal lifeform native to the "Leola root planet" located in the Delta Quadrant.

They were the only "unexpected lifesigns" Chakotay picked up with his tricorder in 2371 when asked by Captain Janeway. Chakotay explained that Neelix wanted to bring some back for a tartar he wants to make, at the time, Chakotay was trying to talk him out of it. (VOY: "State of Flux")