Pi, the mathematical ratio of a circle’s circumference to its diameter, is a universal constant—much like our global love for pizza. As we celebrate one of the most beloved circular foods this Pi Day, here’s a look at some favorite pizza toppings around the world.

1. Nothing

Well, not strictly nothing, but nothing more than the essentials: Italy’s classic pizza margherita relies on the excellence of its basic crust, sauce, and cheese to create a dish that really shines. Made with high-quality flour, fresh mozzarella, and whole tomatoes, the margherita don’t need no stinkin’ toppings.

2. Cheese

…but not just any cheese. While the American mainstay for pizzas made at home or delivered to the front door is shredded mozzarella, other countries promote local favorites atop their slices. India favors paneer, a mild, fresh cheese that doesn’t melt, but is soft enough to give way with each bite. Israel uses labane, another soft cheese with a tangier bite to it from its strained-yogurt base, and not pairing the cheese with any meat toppings keeps the pizza kosher.

3. Mockba

Named for the capital city of Moscow, Russia’s unusual combination of sardines, tuna, mackerel, salmon, and onions—“mockba”—is heavy on both fish and strong odors. A relatively less smelly option might be a simple red herring pie.

4. Eel

The Japanese have another favorite fishy pizza topping: eel. The underwater delicacy is often found in combination with some type of squid, either as another topping or in the form of squid ink as a replacement for red sauce. In this case, it’s especially important to brush carefully after lunch.

5. Mayonnaise

Another offbeat creation from Japan, the “mayo jaga” pizza combines the formidable caloric qualities of mayonnaise and bacon with the additional carbs of potatoes to create a pizza that will really settle down in your stomach for the long haul.

6. Canned tuna

It’s not just for smelly lunch sandwiches anymore! In Germany, the humble chicken of the sea is one of the most popular ways to finish off a pizza.

7. Crème fraîche

A specialty of France’s Alsace region, a “tarte flambée” eschews the traditional tomato sauce in favor of crème fraîche: a soured cream, milder than what Americans consider “sour cream,” that doesn’t curdle under high heat. It is traditionally topped with thinly sliced onions and lardons (strips of savory pork fat) or bacon, though subtypes of the “pie baked in flames” may swap in mushrooms for a vegetarian variety, or apples and cinnamon for a dessert pie. It is more commonly found in a rectangular rather than a circular shape, but it would probably be just as tasty shaped like an octagon.

8. Fried egg

Although the French are said to have originally thought up this simple pizza topper, it’s also an easy excuse in any country to have pizza for breakfast.

9. Emu, crocodile, kangaroo

Meat lovers’ pizza has nothing on this: With its abundance of edible wildlife, Australia frequently serves up its tomato pies with any number of exotic animals on top, often with barbecue sauce.

10. Pepperoni

The spicy sausage remains supreme at the top of Americans’ favorite pizza toppings, despite its shameful pseudo-Italian origins. There’s just no arguing with a classic.

Not mentioned above are certain nationalities’ habit of eating pizza with a fork and knife. What might be considered a horrific social gaffe in certain diehard pizza neighborhoods (looking at you, NYC metropolitan area) is considered good practice in countries like France, Sweden, Norway and Italy. For proponents of the slice-and-hold style of pizza-eating, a good pizza cutter is essential: this pi-shaped pizza cutter from the mental_floss store should do the trick, no matter how you slice it.