it looks like an 'earth apple' a fruiting body of a fungis.

Is the outer skin hard or softish. If the latter I would go along with earth apple/ball but it reminds me of a woody shelled oak apple. Pictures are good but it would be nice to be able to touch it :-))) I have never tried to smell either.
Ah-ha, I have just noticed that you are in China, so it could be something completely different.

Thank you，seaburngirl and bulbaholic。I have get its name，and it is a kind of nut like mangosteen，which have a perfect taste。
it is Beneficial to health，and have a good medicinal value with less toxicity too.
In china ，we also treat it as a flavor.
But it grows only in a special little area in with high altitude、moist and narrow air temperature weather in china。
BY the way i had seen earth apple in early years too.