Got it from the local co-op, no idea what it is! I assume it's some sort of squash. It's about the size of a medium-large orange.
That's a cue ball zucchini.
It's similar to a one ball zucchini (yellow), and an eight ball zucchini (dark green, almost black). All of them are round and great squashes to stuff and roast. Hope you enjoyed it!
The fruit from the Cucurbit family (pumpkins, squash, zucchini, melons, gourds etc) are all very good at cross pollinating. This will create some very strange fruits.
I have accidentally grown all kinds of odd things. I would imagine that they are more common at markets & places where people sell produce grown on smaller (than commercial scale production) plots or gardens. This is because proximity is a contributing factor with wind & insect pollination.
I don't recognise this particular one but it could easily be hybrid. Was it the only one of its type or was there a whole crate of them?