This fruit reminds me of my childhood. I often bought them when I was in elementary school. In West Sumatra we call them kalimuntiang. I even don’t know what they’re called in bahasa Indonesia. I can only find them in West Sumatra though. My mom said that they could be found in the forest on the hills. I think I can say that they are the “forest fruit” of West Sumatra. 😛 Some friends said that they look like mini manggis (purple mangosteen). But in my opinion, they more like blueberry. However blueberry is sweeter than kalimuntiang.