Crumple horned snorkacks are creatures that the Lovegood family believe in. Most likely they are not real
Dillusions of an eccentric, open-minded wizard by the name of Xeno Lovegood, and possibly others. In adulthood, Luna became a magical zoologist and naturalist, even married a decendant of Newt Scamader, author of Fantastic beasts. Though she discovered many new magical species hitherto unknown, she was forced to admit that many of her father's ramblings, the snorkack among them, were not real.