Physiology and culture Edit
Lurians were known to have multiple hearts, (DS9: "Through the Looking Glass") four lungs at the minimum, (DS9: "The Sound of Her Voice") and two stomachs. As a result, they were not only more resistant to damage than most species, but were also able to withstand poisons and other toxins much better. They were able to store liquids in their second stomach for many years, if necessary. (DS9: "Who Mourns for Morn?")
The average Lurian was approximately the same height as the average Human (perhaps a few centimeters taller), but had a much broader and heavier body. Lurians were grayish- or tan-skinned beings descended from mammals. Their most noteworthy feature was their narrow, elongated heads. They had wide mouths, puggish noses, and small, deep-set eyes. (DS9: "Who Mourns for Morn?", "Emissary", et al.)
Background information Edit
The species name "Lurian" was thought up by Mark Gehred-O'Connell and made its canon debut in "Who Mourns for Morn?". Gehred-O'Connell was permitted to name the species (and invent the idea of them having two stomachs) even though he was a freelance writer. (Star Trek: Deep Space Nine Companion, p. 524)
The name of the species was first used in The Making of Star Trek: Deep Space Nine (1994).
It took multiple tries to perfect the Lurian appearance before one particular look was settled on. As such, several heads were made for Morn to appear in DS9: "Emissary". "[They] have not been seen since," laughed Makeup Supervisor Michael Westmore. "That's because some of the heads they [the DS9 producers] felt were a little too far out, that they weren't quite Star Trek." (Star Trek: Communicator issue 123, p. 29) Ultimately, Morn's prosthetic head was sculpted by Vincent Niebla,  who won an Emmy for his work at only twenty-one years of age.  According to Westmore, the mouth part of the Lurian headpiece was designed so as to allow the actor playing him to speak, should the need arise. However, no Lurian ever spoke a single word on Star Trek: Deep Space Nine. ("Michael Westmore's Aliens: Season Four", DS9 Season 4 DVD special features)