Brain Worm

Also, there is this quatrain in your impressive lyric, "Sea Tombs":
Their spires underlie our deepest graves;
Lit are they by a light that man has seen.
Only the winged worm can go between
our daylight and their vault beneath the waves.
Fritz Leiber


The winged brain worms inhabit networks of tunnels that lie beneath the oceans floors. They seem to function as the thought or forms of dreaming Cthulhu. His dream incantations.
Like Cthulhu they probably exist contemporaneously in the many facets of the Multiverse.
Though they travel the tunnels, like mighty cthulhu they also move through the interstices of the rock matrix ~ "Not in the spaces but between them"~
Some that have been noticed by them have been noticed by them have been with their face, jaw and for brain eaten entirely away seemingly by a combination shark-like teeth and some strong, corrosive acid.