Peregrine City 2018
The Vel-Jir are a race of humanoid aliens native to a far-off star but currently inhabiting Antarctica. Contact with them is limited and all but the most superficial details of their physiology and psychology are unknown to humans.
The Vel-Jir appear to have some conscious control over their form, but their shapeshifting appears to be mostly limited to minor changes. Their natural form is a tall, slim humanoid figure. Patches of their skin seem crystaline, looking almost like it was sculpted from smooth glass, and it transitions smoothly to the more "normal" fleshy parts. Their skin tones (crystal and organic) range from blue to purple. They lack hair, and to humans their features look very similar. Those who aren't familiar with them can usually only tell them apart by skin color and crystaline pattern (they apparently have similar difficulty distinguishing humans).