Hammerhead Flatworm is a Predator!

The Hammerhead Flatworm kills and eats earthworms, exclusively! It is considered a parasite and eats the entire earthworm. Do not chop up this worm in trying to eradicate it as they will regenerate from the pieces and you will soon have many Hammerhead Flatworms instead of One. Eradication treatment methods include: salt, vinegar, and citrus oil applied directly on the Hammerhead flatworm.

http://en.wikipedia.org/wiki/Bipalium_kewense