Q: Where’s the worm?
Mezcal has the worm. While being the same as tequila, it can’t legally be called Tequila unless it’s made in one of the 5 special states in Mexico. Same reason you can’t call Champagne, Champagne unless it’s from Champagne. It’s just “sparkling wine”.
The “worm” (actually a caterpillar) was added just for fun. Some places add other odd things, like toes or fingers (not kidding) – you get in trouble if you swallow them in some cases because they’re reused.