The purple worm is akin to an enormous (5 feet wide and tall and 80 feet long) and bizarre earthworm. As its name implies, it is a deep purple color, with a pale yellow underbelly. Separating the yellow part from the purple are hard crests extending down its sides. It is well armored and segmented. One end terminates in a large toothed mouth with slit-like eyes above it and dragon's ear-like limbs at the sides; at the other end is a deadly stinger. The creature is often depicted as bursting out of the ground and arching itself in a distinctive pose.
Purple worms spend their time burrowing through the underground and seek to consume any organic matter they find. Their favored and most feared method of attack is swallowing prey whole. Many groups of adventurers have succumbed to such a fate, disappearing down a purple worm's gullet one after the other. They can also attack with their tail stinger, and by grabbing and grappling with prey.
Purple worms cannot speak. They are regarded as neutral in alignment, since their aggressive nature is the result of instinct rather than maliciousness.