This strange edible is not sold in the market in Apia. Instead, it was gifted to us by our friends Marco and Marie Ines, who have a plantation in the mountains. So this is growing in Samoa, but possibly only on their plantation.
Marie Ines calls it a rollenya, which originally led us to believe the name was Spanish. However, she said it was not and she was correct. However, it is most typically grown in South American countries.
After much research, I discovered a genus of plant called Rollinia. The rollinia genus is inside a family of plants called Annonaceae, which includes the soursop (which we covered in an earlier Name this Plant post) and the sugar apple. Wannabe Farmer thought our plant was an Atemoya, which happens to be a man-made hybrid that includes the sugar apple. So as you can see, many people were in the right family, but didn't hit the nail on the head.
The biriba was described by Cale, Dan and Paul (who ate it) as having the texture and taste of sweet gravy. I cannot even imagine what that means.
According to Purdue University's Horticulture web site, the fruit is regarded as refrigerant, analeptic and antiscorbutic. The powdered seeds are said to be a remedy for enterocolitis.