This is a Canistel, a tropical fruit originating from Mexico and the rest of central America. It is sometimes called eggfruit because of its texture which is apparently scrambled-eggy. I've not seen many of these around, this one was in a botanic garden but notwithstanding how heavily a small plant was fruiting, they don't seem popular. If I were ever to own a Caribbean garden (in addition to a vast array of cycads), I think I'd definitely give one a go alongside the more traditional avocados, bananas and mangoes. There are a few more tropical fruit in the archives to come but the canistel actually fits into another of my categories of interest. Inside that fruit are some chunky seeds and the shape of fruit and seed illustrate the environment the Canistel developed in. Its another of those plants which hints at the dead American megafauna. I have a more detailed post on this issue to come soon too. Once work settles down you can expect some more structured, interesting content than the current daily hit-and-runs I promise!