Thaalud, often called "tomb tappers", were 15 ft (4.6 m) tall intelligent constructs designed to procure magic items. Naked, sexless, and hairless, they possessed hard, smooth blue-gray skin, claws that could dig through solid rock, and great toothed maws in their bellies. They communicated by means of a humming sound created by skin vibrations, a language partially understood by Illithid, and by 120‑foot-range (37‑meter) telepathy. They could detect magic at will, and would burrow through solid stone using their mawed bellies to access magic items.
Tomb tappers received their name from their habit of burrowing into the depths to plunder tombs, temples, and caves in search of magic items, which they carried off to their master. They usually tried to seize magic from living beings that they encountered as well, having little respect for the difference between a living or a dead owner of a magical object. Magic was sacred to a tomb tapper; they never used any magic gained, instead choosing to protect and venerate such items.
Often found in the Underdark, thaluud saw via sonar (emitting inaudible sound much like a bat) that was accurate up to 440 feet (130 meters), making them susceptible to silence spells. This sense enabled them to locate invisibility and displaced creatures and objects, and it made them immune to visual illusions and other vision-related spells; additionally, they were immune to other effects that constructs strandardly were not affected by.
These creatures attacked any threat with iron-hard, long-fingered hands that delivered massive damage, and also hurled itself atop opponents to bite with its abdominal mouth. If it didn't want to close with opponents, it used a great, 10-foot-long hammer of arenite, a magma alloy harder than most rock. A tapper could wield this weapon one-handed and throw it with great accuracy, then re-summon it back into its hands.