The continents we live on today are moving, and over hundreds of millions of years they get pulled apart and smashed together again. Occasionally, this tectonic plate-fueled process brings most of the world’s landmasses together to form a massive supercontinent.

There’s no strict definition for a supercontinent, but researchers like Joseph Meert, a professor of geosciences at the University of Florida, say they should include around 75% of the available landmass.

Scientists are still debating how many supercontinents have existed in Earth’s history, but they’re sure of at least three. Here are all of the known supercontinents that have existed and a few honorable mentions. Live Science spoke with Meert, to check the dates of the supercontinents on this list, but keep in mind they’re still only estimates.