You can buy a 54-pound Martian rock for upwards of $2 million in an auction also featuring a juvenile dinosaur that’s 11 feet long

For sale: A 54-pound (25-kilogram) rock. Estimated auction price: $2 million to $4 million. Why so expensive? It’s the largest piece of Mars ever found on Earth.

Sotheby’s in New York will be auctioning what’s known as NWA 16788 on Wednesday as part of a natural history-themed sale that also includes a juvenile Ceratosaurus dinosaur skeleton that’s more than 6 feet (2 meters) tall and nearly 11 feet (3 meters) long.

According to the auction house, the meteorite is believed...