At this, the veela lost control. Instead of dancing, they launched themselves across the ﬁeld and began throwing what seemed to be handfuls of fire at the leprechauns. Watching through his Omnioculars, Harry saw that they didn’t look remotely beautiful now. On the contrary, their faces were elongating into sharp, cruel-beaked bird heads, and long, scaly wings were bursting from their shoulders — “And that, boys,” yelled Mr. Weasley over the tumult of the crowd below, “is why you should never go for looks alone!”
From J.K. Rowling in Harry Potter and the Goblet of Fire.