Horrid Heart Worm is a common Germ Worms Trashie from Series 7.
Horrid Heart Worm is a worm wearing a heart like a shirt.
This wacky worm is a bit of an alright guy! He has a huge heart but it's covered in so much gunk and ooze that hardly anyone ever gets the chance to see what a nice guy he really is.
Horrid Heart Worm is a play on the real life parasite called Heartworm.