This vile, grayish-tan tubeworm is longer than a man. It has six eyeless heads, and each mouth is lined with inward-curving, serrated teeth. Six long grayish-tan tentacles protrude from the middle of its body.

The terrifying riptide horror is a giant, sightless tubeworm found in sea caves or deep within desolate marshes. They are carnivorous creatures and have a voracious appetite that is only sated with meat, preferably that of warm-blooded humanoids or reptiles.

Opportunistic ambush hunters, riptide horrors wait for prey to come to them. They can go several weeks without eating, and sometimes do, but if a meal is readily available, the horror does not hesitate to kill and devour it. Such a meal is placed in a "reserve" stomach-like sac. When the food supply is low, the riptide horror delves into its reserve and draws sustenance from the stored food.

Riptide horrors mate once a year, usually in flooded sea caves. The female crawls into the male's lair and deposits a sticky, greenish-tan mass of eggs on the wall of the cave. The male fertilizes the eggs, and in 4 months, the eggs begin to hatch. Juveniles are excellent swimmers and leave the cave as soon as they hatch. As a riptide horror ages, its body secretes a substance that forms a shell-like carapace on its dorsal side.

Riptide horrors prefer to attack from ambush; sitting unmoving until potential prey moves within range. Often, they use their Spider Climb ability to cling to sea cave walls where their unsuspecting prey walks underneath them. Once prey wanders too close, the riptide horror lashes out with its tentacles and attempts to grab its meal. Grabbed foes are subjected to its paralytic poison and are bitten by its razor-sharp teeth.