Drayan
From Memory Alpha, the free Star Trek reference
The Drayan people are a humanoid race from the Delta Quadrant planet Drayan II. They were encountered by the USS Voyager in 2372.
In appearance they are humanoid with only a scaly, triangular patch at the center of their hairline to differentiate them from Humans. They wear drab clothes and cover all exposed skin with a thin black veil.
They are warp-capable, but several generations ago decided that their obsession with technological improvement was harming their species. As a result they have withdrawn into their own system and hardly ever make contact with other species.
They believe that the body is merely a reflection of a higher existence and put this belief into practice with their death rites. Unusually, the Drayan aging process is the reverse of that of Humans. Their elders appear to be children. Around their ninetieth year they feel a call to a cave on one of their moons and go there to die. The process of their death is uncertain but they leave no bodies, only a pile of clothing. (VOY: "Innocence")
