Most arachnids operate independently, but ones touched by the Crimson, the region surrounding the brain of Cthulhu's lair, coordinate together to consume life. These giant spiders have abdomens bloated with blood and large, unsettlingly human eyes clouded with cataracts. They seem to arise when mites or other parasitic arachnids enter the Crimson and feast on the abundant flesh and blood. Blood crawlers prefer to live underground, feeding quietly until disturbed.