Shoggoth

" It was a terrible, indescribable thing vaster than any subway train—a shapeless congeries of protoplasmic bubbles, faintly self-luminous, and with myriads of temporary eyes forming and un-forming as pustules of greenish light all over the tunnel-filling front that bore down upon us, crushing the frantic penguins and slithering over the glistening floor that it and its kind had swept so evilly free of all litter. "

— H. P. Lovecraft, At the Mountains of Madness

A shoggoth (occasionally shaggoth) is a fictional monster in the Cthulhu Mythos. The beings were mentioned in passing in H. P. Lovecraft's sonnet cycle Fungi from Yuggoth (1929–30) and later described in detail in his novella At the Mountains of Madness (1931).

The definitive descriptions of shoggoths come from the above-quoted story. In it, Lovecraft describes them as massive amoeba-like creatures made out of iridescent black slime, with multiple eyes "floating" on the surface. They are "protoplasmic", lacking any default body shape and instead being able to form limbs and organs at will. A typical shoggoth measures 15 feet across when a sphere, though the story mentions the existence of others of much greater size. Being amorphous, shoggoths can take on any shape needed, making them very versatile within aquatic environments.