While there has been no direct observation of the Fey, researchers have uncovered several depictions of the Fey in their art and writings. Through these pieces, it has been determined that the Fey were a widely diverse species of peoples, though there are several commonalities that can be stated with relative certainty. All Fey were small in stature, with evidence from Fey ruins that their average height was somewhere between 25 and 45 centimeters.

Records deciphered by archaeologists have uncovered that the Fey seemed to have categorized themselves into three main sub-species. These sub-species are as follows: Insectoid, Arboreal, and Mineral. Of specific interest is evidence that shows that the latter two sub-species were created by insectoid Fey with the help of magic. All three sub-species are covered in the same records and given equal weight, so it appears that they were created as equals and not as subservient beings. It is unknown exactly when arboreal and mineral Fey came into existence, but archaeologists estimate that they were first created towards the end of the era of growth in Fey history.

Insectoid Fey were the most prevalent sub-species. As their name implies, they shared many attributes in common with insects: these attributes included having six limbs, chitinous exoskeletons, and a three-part body consisting of a head, thorax, and abdomen. Some depictions show insectoid Fey with wings - typically two attacked to their thorax - and many more depictions show them having antennae. However, a key distinction between insectoid Fey and insects is that the former were distinctly anthropomorphic in nature, either standing on two legs with four arms, or standing on four legs with two arms.

Insectoid Fey seemingly sorted themselves into several distinct categorizations, as can be evidenced in some records uncovered in Fey ruins. These categorizations include the following: beetles, bees, moths, ants, mantises, katydids, and dragonflies. It is uncertain if these classifications had any further separations between the many species of insects encapsulated in each category, though it seems unlikely.

Arboreal Fey took the appearance of anthropomorphized plant life. It is unknown the extent to which this covered, but direct depictions have been found that show a few particular examples; these examples include a variety of flowers, grasses, shrubs, and mushrooms. The style of anthropomorphization does not appear to be consistent, as some recovered images depict arboreal Fey being as if a plant itself had been given limbs and other anthropomorphic features; while others show more typically anthropomorphic bodies with the plants in question growing out of those bodies. It is uncertain if both of these kinds of arboreal Fey actually existed, as no records make any distinction between the two in official writing.

Mineral Fey are depicted as having been clumps of earth and rock pulled together into a roughly anthropomorphic shape. There does not appear to be as much variety as seen in insectoid or arboreal Fey, as all depictions of mineral Fey seem to represent them with a large, bulky body sporting two arms and four legs, with no distinct heads or facial features shown whatsoever.

Not many specifics are known about Fey biology. It can be assumed by the existence of their civilizations that insectoid Fey biology differs in several distinct ways from the insects that they held similarities to; for example, their lifespans would necessarily be much longer to have created such civilizations and culture. However, there have been direct records showing insectoid Fey biology behaving in similar ways as well, such as oviparous reproduction, i.e. reproduction via laying eggs, and early stages of some categories of insectoid Fey starting in a larval state and undergoing either a gradual or complete metamorphosis.

Records covering the biology of arboreal and mineral Fey are much sparser than those of insectoid Fey, and little has been gleaned into this subject. It is believed that this is due to the creation of these sub-species happening in close proximity to the turning point of Fey civilization that led towards their decline.