mystery funky fruit from the Amazon

cross-posted from: https://slrpnk.net/post/24489864

I recently received seeds of a strange funky fruit from a friend in the Amazon. We have no idea what it is, and Jim West can't tell from the photos that my friend sent to him either. There was a delay in getting the seeds here, but I stuck them in some soil two days ago, and they are already starting to sprout, so they seem like survivors!

It's a medium-small tree that fruits in February/March at ~800m elevation in SE Ecuador. If anyone knows what it is, please don't hesitate to comment.