|Picture from Paranormal Animals of North America|
The Rockworm (Vermes Saxi) are awakened versions of the typical nightcrawler worm. Much larger than their cousins, they have also developed trilateral mouths with grinding teeth and horny plates that resemble rock drill-bits used for drilling for oil. They digest rock and stone, gathering the minerals they need to survive from the digested materials. Their corrosive saliva and the formation of their trilateral mouths mean they can burrow through any type of rock, including granite and man-made ferrocretes and concretes.