I got this 45-hour breed about an hour ago. I did not have a goal to breed it. According to my shop, the Crystal Unicorn and its Gem Grove habitat both unlock at Level 15. (How can you breed something before it unlocks?)
Without speeding, the breeding and hatching will take nearly 4 days. Hopefully, I'll reach Level 15 by then.
All this is assuming it can't be something else.