Closely related to both Custard Apples and Sweetsops, Soursops are Annona muricata. Fruits of all three species share the same basic structure and have a somewhat similar taste, but they look different. That's a Soursop fruit below:
Soursop fruits are a bit acidy, as well as juicy. They're whitish inside and fragrant. They're used mostly for making sweetened, fruity drinks, and for making into preserves. Traditionally the juice has been considered a remedy for dysentery.
This is another native Mexican -- but not from the Yucatan -- species that has been planted in the tropics worldwide.