This is a Cucumis metuliferus also known as a Kiwano or Horned Mellon. These are native to sub-saharian Africa and taste like a hybrid of zuchini and cucumber.
This is an entry to [Sketchfab's January 2017 scanning challenge](https://blog.sketchfab.com/monthly-3d-scanning-challenge-horn-plenty/). Created via 127 photos captured with Nikon D3300 and a 18mm-55mm kit lens. I used autofocus and shot at f/13. 1.1m -> 50k