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!

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.

In some animals the protective layer on their eyes is a darker color, possibly even black in appearance. This adaptation is theorized to hide eye movements in predators or even act as 'gaze camouflage' for social species hiding where they may be looking from others around!

In some Xeros, the tapetum lucidum that gives them such excellent low-light vision undergoes a dramatic mutation. Bright pupils are the result of this highly reflective tissue, causing it to reflect in such a manner to create this striking appearance! This trait allows a Xero's pupils to be lighter in color than the iris (the main colored part of the eye). The bright pupils can be any color, so long as they are lighter in value than the iris.

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.

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.

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

Folded Ears are a common mutation observed on Xeros. These ears can be various shapes and sizes depending on other mutations present, but feature ears that are bent or folded in some way.

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.

Round Ears are a unusual mutation observed on Xeros. These ears are very circular in shape, rather than the elongated, diamond-like shape Xero ears typically are.

Lop Ears are an uncommon mutation observed on Xeros. Xeros with these ears lack structural cartilage and muscle control, leading to fully hanging ears like the ears of a lop rabbit.

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!

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.

Marine Xeros can have extra small ears, or no visible ear flaps at all. This adaptation helps them be more streamlined underwater. If combined with the Marine Fin trait, they can have fins instead of ears!

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

Horns are a rare trait for a Xero to have; these keratin-covered bones grow in pairs from the top of the Xero's head. Much like the antennae, horns can be many different shapes and lengths. Horns can only be found in symmetrical pairs and only on the top of the Xero's head; for keratinous growths on other areas of the Xero's body, see the Spines trait.

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!

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

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.