Are these unripe jujubes?
(My guess based on an internet search for Taiwanese fruits.)
I got them at an Asian market. First time I've seen them there.
The register clerk said he had no idea what they are and that it was the first time he's ever seen them (I'd say he's in his late 50s or early 60s). Another employee at the store said she didn't know either. A shopper didn't know the English name for them but said they can be eaten out of hand as a snack.
Also, any suggestions for how to enjoy them?