Name that fruit or vegetable

I suppose it should come to me as no surprise that there are fruits and vegetables down here that I wouldn’t find back home in the States, but it never ceases to amaze me. From time to time my host family will put a bowl full of a vegetable soup in front of me and I start trying to figure out what exactly I’m eating. One popular vegetable is called Guicoy and it’s a cross between a potatoe and a cucumber. There are tiny little apple like fruits called Guayava and there is a little nectarine like fruit with at large seed in the middle. I feel kind of silly having to ask whether you eat the peel (and seeds), but I guess you just grow up learning that with the fruits you encounter in your youth. Any guesses on the fruit in the photo?