Sumo Citrus oranges look like regular old oranges with a big knot at the top, but they're a non-genetically modified hybrid of navel oranges, pomelos, and mandarins. These fruits were developed in Japan in the 1970s, and California farmers later started growing Sumos from imported seedlings — not that this has made them cheap.

Sumo citrus oranges can sell for up to $5 per pound, compared to an average of about $1.49 a pound for navel oranges. Sumos are delicate fruit, and their trees require more pruning than other citrus plants because each individual piece of fruit needs access to sunlight (but not too much) in order to thrive and reach its peak sweetness.

Sunnia Gull, director of brand management at AC Brands, which owns Sumo, says that “The trees are hand-pruned and trimmed [...] The skin of the Sumo citrus is actually so delicate that there's this sort of clay that is put on, a sunscreen, over the summer.” This fruit's unbelievable sweetness is special, but its upkeep is what really jacks up the price.