On their icy worlds the Muuh have constructed spa-like structures that utilize liquid methane containing the complex organic molecules collectively known as tholins. Tholins form a sludge that is brownish-red to human eyes, and though in time they settle out of a methane solution they can be kept in a soup-like suspension under certain conditions.
Most Muuh enjoy bathing in such mixtures for hours or even days at a time. It is thought that such liquids mimic the products of natural "hot springs" on the ancient home world of the Muuh. Most Terragens, of course, find the idea of such a "hot" bath (-160° Celsius or so) quite unappealing, despite the rapturous descriptions of the experience in Muuh poetry. Natural tholin spas are highly valued on Muuhome, and artificial equivalents are considered an essential element in Muuh living quarters.
Ruins of a two million year old tholin spa have been found buried under layers of ice on Titan. The ruins apparently date back to the days when the Muuh once had a colony in the Sol System. Two Muuh, known as "Hooclick" and "Missy Muuh" have lately taken to conducting tours of the site, either in person for real visitors to Solsys or as avatars for virtual visitors over the Known Net.