“The caverns and passages are naturally very tortuous. A large proportion of these ways are known only to expert pilots among the fishermen, and not infrequently Selenites are lost forever in their labyrinths. In their remoter recesses, I am told, strange creatures lurk, some of them terrible and dangerous creatures that all the science of the moon has been unable to exterminate. There is particularly the Rapha, an inextricable mass of clutching tentacles that one hacks to pieces only to multiply; and the Tzee, a darting creature that is never seen, so subtly and suddenly does it slay.⁠ ⁠…”

He gives us a gleam of description.