I compost the remains of fruit and vegetables, and this supplies nutrients to the soil, and also some plants come up from the seeds in the compost. Most of such plants do not survive long, but occasionally something does. Sometimes passionfruit do, papaya very often do, and recently a vine has been prolifically growing, presumably from seeds from the compost.
The vine spread first on the ground, and then started climbing, and quickly grew around the passion fruit vines, and up high. Then big yellow flowers appeared. They dropped off after a few days.
Later a small green vegetable started growing, with a flower on top of it. It is like a small courgette or pumpkin.
I couldn’t pick it as it was firmly attached to the vine. Eventually, after a few days it turned yellow, and then a day later yellow/brown, and it could easily be picked. But by that time it seemed to be already decomposing inside – so no longer suitable for eating.
So we cut them off while green, and tried eating a little – we didn’t want to poison ourselves. The taste is like a rich courgette. We didn’t get sick.
We have no idea what it is, and whatever it grew from is not what we composted. Perhaps it is the natural form of something we eat, and has reverted to type.