This is a Singra
It looks like a dried skull or very wrinkly prune. You see them in the market, laying in large piles next to cauliflower and spinach.
It was pretty easy to crack open and pull the white "nut-like" fruit from the shell.
It has a crisp bite and tastes a lot like raw corn on the cob. Corn on the cob with a dash of coconut or chestnut. It has a mildly bitter after taste, but is over all quite pleasant. It has that kind if flavor that reminds you of a family holiday, like they would be arranged in a bowl on the coffee table, accompanied by another empty bowl to hold the discarded shells. Only occasionally would everyone would eat a few.