TOS s2e15 “The Trouble with Tribbles”
It’s any wonder there wasn’t a second Klingon/Federation major conflict prior to the Dominion’s presence after Scotty transported the mass of tribbles from the Enterprise onto the outgoing Bird of Prey right before warping away. But hey, gotta end it on a light-hearted moment.
It was the Tribble of Caerbannog. A foul, cruel and bad tempered floofball! It killed six ships with its big and pointy teeth! GRrrrrr!