A curious Si'lahn named Fi'lrehiin (right) inspects a brightly colored Hal'puno specimen (left).
The Si'lahn race come from the arid and rocky regions and have a natural interest in the world they live on. Uncovering new knowledge brings a Si'lahn a satisfaction that's only barely palpable to the average Human.
Si'lahn inspect their world through their many sensory organs, including 6-18 the whisker-like antennae they have on around their skull-equivalent anatomy. As a child, a Si'lahn individual begins life with only the bottom six antennae closest to their mouth. As they mature, they grow the additional antennae and the original 6 get replaced by new growths as they age.
This social race relies heavily on verbal, written and pheromonal communication. Behind the feather-like structures are several glands that are used by the Si'lahn (both sympathetic and parasympathetically). The natural hood of the Si'lahn both acts as a amplifier for these pheromonal signals and a source of protection from their sun's radiation.
In contrast, the much smaller Hul'puno lacks many sensory organs and is suspected to rely on a type of thermal 'vision' using their much thinner frontal skin when exploring their terrain (as this Hal'puno is doing here).
While there are many discoveries to be made about the tiny Hal'puno, when asked what Fi'lrehiin was observing, he simply replied "I find her colors beautiful. I wondered if she thinks of herself as beautiful as well."