Brimstone Thornworm

The Brimstone Thornworm has taken advantage of the abundant food source provided by the plaque of sulfur-metabolizing bacteria around deep sea vents. To this end it has a thick mineral carapace to protect it from the heat around the vent. This hinders its movement, but movement isn't a great requirement in this environment. Over time, sulfur crystals grow on the backs of these creatures, with some of the oldest being up to a centimeter in size, and almost totally encrusted with brimstone.