These creatures largely resembled iguanas, though much broader. Their bodies typically grew to be 15 to 20 feet (4.6 to 6.1 meters) and 5 to 10 feet (1.5 to 3 meters) wide, with tails that were 8 to 12 feet (2.4 to 3.7 meters) in length. Their skin was mottled and had a dull olive-gray hue, but their flesh was said to resemble very dense, white pork.
Their jaws were very powerful and contained a long, probing sticky tongue. Their splay-toed feet had flexible, very vulnerable digits. They were covered in horny, protective sheaths that resembled claws, but were virtually useless in combat. Beneath their feet were sticky pads that allowed them walk across any surface in their subterranean habitats with ease, even walls and ceilings.
Early scholars described subterranean lizards as being very aggressive and hostile, though pack lizards were generally rather placid and very lazy. They were often attracted to the stench of carrion following large battles in the Underdark.
These creatures possessed an immunity most known forms of poison, the mild regeneration typical of lizards, and some resistance towards harm from fire. However, they were vulnerable to cold-based spells.
Pack lizards could carry very heavy loads of supplies. A small load for them was roughly equal to and below 800 lb (360 kg), a medium load capped off at 1,600 lb (730 kg), and the heaviest load they could manage was 2,400 lb (1,100 kg). They were capable of carrying small loads while walking across a ceiling, while they could only carry medium loads up 45 to 90 degree angles.
Pack lizards could even carry loads through areas that were quite damp or cold, so long as they had respites of warmth. Such as from deserts or sun-baked mountain rocks on the surface, or volcanic activity underground.
Pack lizards were very skilled at hiding, especially in their natural underground habitats. When they had to fight, pack lizards used their crushing jaws, clamping down with their terrible teeth. Often they would pin their smaller opponents down, holding them in place with their sticky footpads.
Around the 14th century DR, Vhurn Bhaelyndryn's Bestiary in the bazaar of Menzoberranzan was known to supply pack lizards and their associated gear. Circa 1480 DR, this establishment was still supplying pack lizards to denizens of the Underdark.
Pack lizards could be found living either solitarily or in packs. When they formed mating pairs, these remained stable for many years.
Throughout their life times these creatures rarely mated, only doing so two or three times a year. They typically birthed litters of two to eight in rubbery-shelled eggs.
These creatures were an omnivorous species willing to eat almost anything, even carrion and grass. If hungry enough, pack lizards were known to bite their way through armor and wooden doors in order to reach food.
Pack lizards were especially fond of scurry rats, snake meat, and the yellow-petaled flowers that were common in meadows. These included buttercups, dandelions, sunflowers, and sunstars. They also were known to eat creatures and plants that were corrosive or poisonous to other species, such as gelatinous cubes and violet fungi.
Much like other species of lizard, the wild subterranean lizard tended to drag its prey back to its lair before devouring it.
These creatures were primarily found underground, though prior to their wide-spread domestication it wasn't rare to find them on the surface. Following their wide-spread domestication, those living on the surface only encountered pack lizards in remote desert regions.
Underground they were typically found to dwell in burrows or caverns near areas with volcanic activity, as their cold-blooded bodies required them to bask in some form of heat.
Gold dwarves (when in underground locales), shield dwarves, drow, and nearly all intelligent races that inhabited the Underdark were known to use pack lizards as beasts of burden, much in the same way that surface dwellers would transport goods in horse-drawn wagons or on the backs of oxen. Some drow mercenaries, noblemen, and warriors also used them as mere steeds.
The drow had caravans of these creatures moving between the trade hubs of the Underdark, protected by warriors mounted atop riding lizards. They were one of the many Underdark creatures that the duergar of Fraaszummdin raised and trained. For the shield dwarves in Iltkazar, riding lizards were the standard beast of burden.
Some used these creatures as neither steeds nor pack animals. Such as the varkha, who had them guard their breeding nests. And many races were known to hunt them for the purposes of food. Their flesh was prized by drow, humans, and especially orcs.
Besides their use as pack animals and food, some material components could be derived from the bodies of subterranean lizards. Their blood was a prized ingredient in potions of vitality while the essence extracted from their feet was a valued component in the construction of sovereign glue. Some form of oil could also be derived from their bodies that Drow were known to fry insects in.
- Ed Greenwood (July 1991). The Drow of the Underdark. (TSR, Inc), p. 112. ISBN 1-56076-132-6.
- Ed Greenwood (1992). Menzoberranzan (The City). Edited by Karen S. Boomgarden. (TSR, Inc), p. 91. ISBN 1-5607-6460-0.
- Ed Greenwood, Sean K. Reynolds, Skip Williams, Rob Heinsoo (June 2001). Forgotten Realms Campaign Setting 3rd edition. (Wizards of the Coast), pp. 308–309. ISBN 0-7869-1836-5.
- Gary Gygax (December 1977). Monster Manual, 1st edition. (TSR, Inc), pp. 61–62. ISBN 0-935696-00-8.
- Eric L. Boyd (November 1999). Drizzt Do'Urden's Guide to the Underdark. Edited by Jeff Quick. (TSR, Inc.), p. 50. ISBN 0-7869-1509-9.
- Ed Greenwood (1992). Menzoberranzan (The City). Edited by Karen S. Boomgarden. (TSR, Inc), p. 48. ISBN 1-5607-6460-0.
- Brian R. James, Eric Menge (August 2012). Menzoberranzan: City of Intrigue. (Wizards of the Coast), p. 90. ISBN 978-0786960361.
- Reynolds, Forbeck, Jacobs, Boyd (March 2003). Races of Faerûn. (Wizards of the Coast), p. 14. ISBN 0-7869-2875-1.
- Reynolds, Forbeck, Jacobs, Boyd (March 2003). Races of Faerûn. (Wizards of the Coast), p. 20. ISBN 0-7869-2875-1.
- Eric L. Boyd (November 1999). Drizzt Do'Urden's Guide to the Underdark. Edited by Jeff Quick. (TSR, Inc.), p. 9. ISBN 0-7869-1509-9.
- Eric L. Boyd (November 1999). Drizzt Do'Urden's Guide to the Underdark. Edited by Jeff Quick. (TSR, Inc.), p. 19. ISBN 0-7869-1509-9.
- Bruce R. Cordell, Gwendolyn F.M. Kestrel, Jeff Quick (October 2003). Underdark. (Wizards of the Coast), p. 150. ISBN 0-7869-3053-5.
- (1998). Monstrous Compendium Annual Volume Four. (TSR, Inc), p. 89. ISBN 0-7869-1212-X.
- Ed Greenwood (October 2012). Ed Greenwood Presents Elminster's Forgotten Realms. (Wizards of the Coast), p. 90. ISBN 0786960345.
- Gary Gygax (1979). Dungeon Masters Guide 1st edition. (TSR, Inc.), p. 223. ISBN 0-9356-9602-4.