Traits are special features that a character may have! They come in different rarities and can be earned by participating in site events and activities to then buy the corresponding trait item. You can then submit a MYO with said trait item, or send a design update request with one if you'd like to add a trait to an existing character. Trait items can be found in shops, so you may want to go window shopping...
Crystallized (Rare) Masterlist Examples
It's not quite clear how, but some individuals have developed crystallized features. This may affect horns/hooves/claws, or a whole limb. These parts may be disconnected or partly floating thanks to magical spells. It may also cause an icy / snowflake aura (as those are ice crystals) around the character, or just floating earthen crystals.
NOTE: This trait can turn a characters existing limbs, or part of one, into a different material. This should never affect more than 50% of the characters main body (the main body consisting of head, torso, arms and legs). Limbs should roughly keep their original shape (wings must still be recognizable as wings, tails as tails, etc).