Mass Effect: Space monkeys and other galactic curiosities

Killer worms

You'll encounter plenty of enemies as you explore Mass Effect's galaxy. From pirates, mercenaries and scavengers, through to the humanoid Geths, the zombie-like Thorian creepers and the cyborgy Husks. However, if you're looking for a slightly more exotic foe, you'll want to seek out a Thresher Maw - a giant space worm that erupts from the ground and spits deadly corrosive sputum. Worth seeking out if just to add a bit of variety to all the standard runny-gunny shooty-shooty combat.

Where to find a Thresher Maw:
Armstrong Nebula - Tereshkova - Antibaar
Hades Gamma - Antaeus - Trebin
Artemis Tau - Sparta - Edolus

See a Thresher Maw in devastating wormy action in the movie below.