At Normal Size:
Hydrothermal vent worms are so tiny that you can't see them. They live around the hydrothermal vents on the abyssal plain of the ocean floor, which is probably another big reason you can't see them:
Oh, they're in there. Waiting.
But Up Close ...
Run, Kevin Bacon, run!
Upon closer inspection, the hydrothermal vent worm (or razorbeak vaginabeast, as we have just classified it, just now) leaves little doubt that the hydrothermal vent in question is a sulfur-belching portal to the plains of the damned. If you told us that this thing snatches the souls of children in the night and ferries them to the underworld, we wouldn't be surprised. Also, try to play it cool, but it's behind you.