The Spawn of the Green Abyss are a fictional race created in 1994 by Chaosium for the Call of Cthulhu RPG, which was based on C. Hall Thompson's The Spawn of the Green Abyss.
Background
The Spawn of the Green Abyss are a highly evolved and intelligence race which lives in the oceans and seas of Earth. Living in societies ruled by their queen, Zoth Syra. They appear as bluish slime whose various features are shifting. Limbs and sensory organs are created as needed. The songs of the spawn can influence those whom hear it. Though normal weapons cannot hurt them, they can be harmed by fire, chemicals, electricity, magical spells, and enchanted weapons.