Troglodytes. Perhaps the OP was thinking of trilobites.
No, Troglobites.
Huh. Ignorance fought. Of course, that was a pretty weak ignorance: had I checked a dictionary before posting, I could have done it myself.
More distantly than what? Many species that don’t live in caves have closely related species nearby. The process could take thousands or tens of thousands of generations, and there might still be “closely related” species around. Based on information from islands that were connected to the mainland during the most recent Ice Age when sea level was lower, full speciation often takes longer than 10,000 years, and may take millions.