The Rasiinian in "The Muse" was played by John Paul Lona. He won a guest spot on DS9 for designing the make-up of the Rasiinian species in the Playmates Toys' "Design-an-Alien" contest.
According to Lonas' winning entry, he described the Rasiinian as having "a boney exo-skeleton which covers his soft, wrinkled skin. His glowing eyes often give away his mood, both varying in intensity and color." (Star Trek: Communicator Issue 105)