Muggles' Guide to Harry Potter/Magic/Demiguise

Overview
Located in the far east, the Demiguise is incredibly hard to find, as it will turn itself invisible if it feels threatened.

Extended Description
It is mentioned in Harry Potter and the Deathly Hallows that many Invisibility Cloaks are actually woven out of Demiguise hair. It is also mentioned that these cloaks become opaque over time.