at the moment i can't double check, but didn't changheng found that firefly stone in the northern most ocean where he was fighting against... xunfeng?

because i was thinking that xiao lan hua told him to give the stone to his future love, but that it wasn't very nice to give someone else what you got for a previous crush

UNLESS there is actually another story with this stone which comes before xiao lan hua and look who was there where and when the stone was found! (xunfeng)