2 out of 3 types of unicorns in rearing redwoods!! they aren't actually different species of unicorn, but instead three ethnic groups of unicorns.

All of the unicorns are inspired by different types of ungulates, the Star Unicorn was partially inspired by some kinds of swine for their tusks. The long coat isn't from any specific ungulate inspiration, I just wanted a fluffy unicorn. Still mostly a traditional unicorn feel for these guys!

(this art will be repeated in all three unicorn bios)
Since their biology isn't much different from a regular horse, there isn't too terribly much to comment on. They aren't born with their horns of course, that sounds like a nightmare, but have a little bump on their heads in the place it'll grow at. The speed that it grows in depends on individuals, early bloomers tend to start around 5 years old, average is usually around 8, and late bloomers start at latest 13 years old. Their horns only grow in once, and if it breaks or gets any damage, there is no repairing it or growing back. I imagine that there might be a market for prosthetic horns for those that have lost theirs.