Thulecite is a material found in Ruins. It is used to craft various items in the Ancient tab and to repair a broken Ancient Pseudoscience Station. Currently, it is nonrenewable, though in theory, one could renew Thulecite by hammering the Ancient Pseudoscience Station and repairing it, since it takes 10 hits to destroy the Station but only 6 Thulecite to fully repair it, and each hit has the potential to spawn Thulecite. The chances of this occurring are extremely low though, so for practical purposes, Thulecite is non-renewable.

Slurtles and Snurtles will attempt to eat dropped Thulecite, and Slurtles will attack a player holding Thulecite if there aren't any other minerals around for them to eat.