they have different horn colors, and being a Red/Green/Blue horned individual is super rare, and if they are a RGBhorn, they take care of the Great & Honored Ketsete and Terra Mater.
Terra Mater is alike the Mothergrub, except she actually is required for the planet to live. She dies without a heir, the whole planet dies.

they have tails and pawhands/feet
they all have the same shade of grey for skin
they all have those fangs
the eyepatterns differ, but all the species have them
they use only their horn colors as clothing, they have hair and clothes as different shades of their horn colors

being a black/grey/white horn is impossible
the blood/eye color depends on the first color in the horn class (i.e. a pink/purple/blue horn would have pink eyes & blood)
they can have white and black in their horn colors, just not together (i.e. Black/white/red would be impossible)
they all have split pupils

females have boo.bs
no two have the same colors
they are raised by a being called the Grand Delti Muuti, all of them.
the babies are called Delti
after 4 human years, called Moon Orbits, the delti become adults
one moon orbit is equivilent to 2 human years.
the birthday is called a Age Shedding

they have tails and paw of earth animals (ie lemur tail/paws on this guy)
they have quirks, but it has to do w/ their horn colors (ie a black/red/orange would capitalize/lowercase letters in black orange and red)