I saw this in the local market and bought 3. You may know it as Sapodilla. The colour of the fruit does not change when it ripens. You just need to gently feel the fruit as it softens when it ripens. It has a distinct sweet taste.
They seem much larger (palm size) from what I remember and probably bred to contain fewer seeds. I found only one or two black seeds in each fruit.
I remember eating this plucked from the tree in my grandmother's garden.