Very deep worms.

[Plane]

The paper's authors have been trying to have a bit of fun with their discovery as well. "We tried to get the title of the paper to be 'Worms from Hell,'" study author Tullis Onstott of Princeton University told LiveScience. "But Nature didn't go for that."

http://www.huffingtonpost.com/2011/06/03/worm-from-hell-discovery_n_871203.html

The discovery of multicellular life in the deep subsurface of the Earth also has important implications for the search for subsurface life on other planets in our Solar System.

http://www.nature.com/nature/journal/v474/n7349/full/nature09974.html

[Xavier_Onassis]

I note that although Nature did not like the phrase "Worms from Hell", they snuck the word "mephisto" into the scientific name.

"Worms from Hell" evokes a properly disturbing image, like "Snakes on a Plane". I see this as a potential Disney film. As I recall, giant worms living under the desert have already been featured in a film. It was called "Holes". Like "Snakes on a Plane", it was hard to keep the excitement going for over an hour. Making the worms smaller and deeper will not make for a more exciting film.

So for centuries, men have believed that Satan lived under the Earth, and now all there seem to be are innocuous worms.