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 monster in the Cthulhu Mythos. The being was mentioned in passing in sonnet XX ("Night-Gaunts") of H.P. Lovecraft's sonnet cycle Fungi from Yuggoth, written in 1929–30, and were expounded upon in his novella At the Mountains of Madness (1931).
The Elder Things supposedly bred shoggoths from some of Ubbo-Sathla's spawn. This begs the question of what the Karotechia were trying to do at Point 103. Make their own shoggoths, perhaps.