Corpsers

No one has ever seen these creatures, apart from the tentacle that suddenly shoots out of the ground to pull the victim under the earth, where it is killed and eaten. The Corpser relies on stealth to sneak to its victim. But once detected, the normal adventurer should have little problem with destroying this abomination.

They can be found in caves and dungeons with soft soil.

Corpsers appeared in Ultima V, VI, VII and VII/2. Their behaviour was the same in all these installments, meaning that it tried to surprise the party and pull someone underground.