Pulasan is a close relative of the rambutan (and lychee). Its outer spines are much more stiff than the rambutan’s, so it feels rough, though not sharp. The spines are just stiff enough to use as leverage in order to peel the fruit, which makes getting into these the easiest version of these fruit relatives so far – just grab on and pull or twist, and the skin comes right off. It doesn’t really have much of an aroma, just a mild sweet fragrance. The edible inside flesh is juicy and springy-soft, like a firm grape. Its flavor is basically just sweet, with no real other distinguishing qualities – it tastes like a mild lychee, but it could also be compared to a very bland grape. There’s a single large seed in the middle of each fruit, which is not eaten. There is a bark-like shell around the inner seed, like a rambutan, but it only sometimes clings to the edible flesh, making this fruit significantly easier to eat.
There is a wikipedia article about pulasan at https://en.wikipedia.org/wiki/Pulasan