Traits

Eye stalks are classified as two protrusions from the head of a Xero that have a cone-like base and two round eyes on top. These stalk eyes are simple ocelli and are primarily used to detect light, dark, and movement all around the Xero, rather than complex shapes or colors. Sneaking up on a Xero with this trait would be very difficult!

Eye stalks must be placed on top of the Xero's head area and must be in pairs, much like adding any other extra body part. The eyes must also match the iris and pupil color of the rest of the eyes on the Xero, meaning that if a Xero has blue irises, the stalks must follow suit!

Some Xeros may have thin, slit pupils instead of the standard round or oval ones. This is an uncommon adaptation, but the Xeros that have this style of eye tend to have even stronger night vision. 

Life in a world of little-to-no light can present several obstacles, arguably the most important being how to sense the enviroment. Hollow Xeros have developed eyes that feature significantly larger pupils and a highly efficient tapetum. These features enable them to operate effectively in the darkest of conditions and give their eyes a soft, reflective sheen.

While Xeros typically feature a static pupil, their flexible biology can be manipulated to overcome this limitation. By altering the smooth muscles of the eye, the collarette can be reshaped effectively, changing the shape until desired.

Tufted Ears are a common mutation observed on Xeros. These ears can be any shape or size, but feature tufts of longer fur at the tips. This adaptation may have allowed Xeros to more easily determine wind direction and stay downwind of danger.

Frilled Ears are a rare mutation observed on Xeros. They have a grooved outer edge, giving them a jagged or wing-like appearance.  

Marine Xeros can have extra small ears, or no visible ear flaps at all. This adaptation helps them be more streamlined underwater.

These ears are unique to Hollow Xeros, and while they fit the shapes and sizes you expect from a standard Xero, they do have an adaptation unique to their type. The ear's interior cartilage is ridged, acting as a type of acoustic focusing lens to help sharpen sounds for positional accuracy in the dark. Hollow ears can be a solid color, or have a gradient of changing colors within the different segments. The ridges within the ear must be present.

Floppy Ears are a common mutation observed on Xeros. These ears can be perky like the above example, fully flopped like a labrador's ears, or even longer flopped ears like a lop rabbit's. 

Tundra Xeros can have extremely fluffy ears called Tundra Ears; the fluff is so long that the tufts of fur inside cover most or all of the visible skin and hangs outside the ears!

Desert Xeros can have larger than average ears to radiate heat, this trait is known as Desert Ears. They can be any shape (pointy fennec-like, rounded jackrabbit-like, etc.) Size can vary a bit, but is generally about 1.5 to 2x the height of the head.

Gills are respiratory organs that are located on the neck or rib area and allow the Xero to breathe underwater. A Xero with this trait has both a set of gills and a set of lungs and can “turn off” function for one or the other depending on their body state.

Gill-having Xeros who spend a lot of time outside of the water are recommended to find ways to rehydrate often to avoid drying out the area.

Warning: this is still highly experimental, results my vary.

Braving the acidic Sugar Drop allows a Xero to stain their teeth any color they desire! The enamel-stained color can also be as subtle or vivid as the Xero wants. Curiously, the Sugar Drop dyes every tooth in the consumer's mouth. This means that the Xero must commit to the same color on each of their teeth and may not mismatch colors. Go all in!

An adaptation for moving swiftly on wide-open grasslands. These hooves are rounded, modified claws whose purpose is to protect the Xeros feet from rocks and difficult terrain while running. Since these hooves can see some extra wear and tear it is recommended to clean them out daily.

Diaphonization is a bizarre mutation in which the skin of the affected area contains no melanoctyes, rendering it semi-translucent to visible light. Organs, veins, and muscles, having the same refraction index, would also appear transparent, but bones, being a denser tissue, remain visible.

Although the effect is fascinating, Xeros with any amount of diaphonization cannot grow fur in those areas and thus their skin is extra sensitive to UV light; nothing a bit of sunscreen can't fix though!

Xero Bone Structure Reference

Antennae are the most common trait displayed by Xeros. These sensitive feelers enhance a Xero's senses and help them navigate in difficult environments. The antennae can be many different lengths, and can be present on the head, back, tail, or on the cheeks like "whiskers".

Jungle Xeros can have patagia - that is, loose flaps of skin connecting from each wrist to hip. These patagia allow the Xeros to glide short distances, such as from tree to tree, or slow their fall like a parachute. Much like the patagia of a flying squirrel, they are extended with the aid of specialized wrist bones and the loose skin can fold up against the body when not in use.

Horns are a somewhat uncommon trait for a Xero to have; these protrusions are hard, shiny, and slightly translucent, just like the Xero's claws. Much like the antennae, horns can be many different shapes and lengths, and can be present on the head, back, tail, and other places, such as on the cheeks, top of the snout, or on the back of the limbs. 

Venomous Xeros are quite rare, and not very much is currently known about why some feature this trait. Scientists speculate that it is a leftover adaptation from their previously insectivorous lifestyle. Venomous Xeros have a pair of modified saliva glands that can deliver venom through grooves in their upper canine teeth. However, they have complete control over these glands, and are able to produce regular saliva the majority of the time, so it does not negatively impact their lives in any way. Even Xeros who do not posess venom are immune to its affects, so there is no cause for concern!

The most notable visual feature of venomous Xeros is that their flesh is a fully saturated, neon color, to serve as a warning of their toxins. They also feature neon-colored markings surrounded with a dark outline for high contrast. These markings can be any shape, such as stripes, spots, rosettes, stars, and more.