Well let's first begin with the basics: if it looks like the head of a bearded man, it must mean an advantage at surviving or breeding or at least that it won't hinder its survival.
My best bet on how a beard could remain looking well treated despite being exposed to the environment is that its not a beard, but more like a hairy growth. Given that this thing is fast for its size (it's the size of a human head, but can move at the pace of a human), as well as the clattering sound, I'd say it could be some kind of alien hybrid of an arthropod and a snail.
Upon picking the creature up, it's clear that the similarities with a human head stop at the creature's back. The beard is actually the main body of the alien, consisting of the had and thoracic region fused into a Cephalotorax, which is covered with a series of hair-like filaments. The cephalotorax also houses 3 pairs of compound eyes located mostly at the top of the cephalotorax (likely to spot aerial predators) and 4 well developed antennae, which indicate the animal relies more on smell and touch than sight to hunt. Upon closer inspection, their hairs are very similar to the nearby beard-looking bushes in the area, indicating how they might hide the "head" shell into the bushes while relying on their own hair-like growths to remain camouflaged, ambushing any unsuspecting prey that happens to get close enough for a strike.
The creature is an alien arthropod which seems to have appeared as a mix of sexual selection and camouflage. It's "head", being in fact a modified shell of sorts, is actually rather hollow, and serves for housing several of its organs, with the nasal cavity actually being functional. The "head"'s nose splits in a system of tracheas much like our planet's insects, which provide oxygen to the tissues and explain the creature's mobility. The "head"'s mouth is actually a large structure with several hard tooth-like structures, which hit against one another to form a clicking sound which the creature uses both to ward of predators and rivals as well as to attract females.
The ears of the "head" are surprisingly home to one set of long tentacles each. Upon closer inspection, the tentacles are much similar to an scorpion's tail, injecting a toxin that isn't dangerous, but is almost as painful as a bullet ant's venom, clearly working as a counter-measure against predators which try to turn the head over. In the underside of the head, 5 pairs of relatively short, yet powerful legs propel the creature at decently high speeds, allowing it to move as fast as a human. The chin region is actually an entry point through which the creature retracts its legs, head and abdomen (the "beard" enters the head) in case a predator arrives or if it feels threatened for some reason, remaining protected inside its hard head-shell.
Lastly, the heads eyes are actually fixed and seem to be looking up, being usually protected by a membrane that reminisces human eyelids, with said membrane also covering most of the head-shell. Upon further analysis, the cause of said trait seems related to the presence of aerial predators, to which a creature out in the open will react by hiding inside its shell, unveiling the eye structures and clattering loudly. Nearby creatures which hear the clattering will rapidly approach and expose their "eyes", creating a peculiar sight of heads staring up. The predators appeared frightened to attack, and have demonstrated similar reactions to tigers regarding behavior, in which they'll prefer to swoop down on prey which doesn't seem to be looking at them.
After reproduction, the females will dig holes in the ground, in which they'll deposit their eggs. Apparently the aliens which approached the researchers were all females, and were merely reacting to them being too close from their nesting ground. The soft skin-like membrane which covers the head and eye structures seem to have been sexually selected.