Mystery Fruit

What you see before you are two shots of the same fruit that has been in question for the past week. I have place it with ordinary objects to give some idea of size and color.


That's a "large" egg on the right, a bowl of cherry tomatoes and a cellphone. I have cut the fruit exactly in half to reveal the seeds within. I can tell you that at this size, this fruit is more tart than sweet but not in an overripe way.... not that tangy vinegary flavor; more of a tart unripened way and slightly more like a honeydew melon than a cantaloupe. And the seeds are clustered exactly like a melon/cantaloupe.
It WAS a lovely sage green until it went all yellow and dropped off the vine.

So Anyone??? Anyone with ideas as to what it is and why it won't grow larger? Is it possible that it came from a GM melon and simply is genetically engineered to not grow beyond this point?