Chinese black olives. Preserved in brine and dried. They are olive-olives but impart a completely different flavour from those of the European variety.
The best Chinese-style steamed fish I've had in restaurants were made with a generous sprinkle of these salty black chopped up bits and I've always wanted to play with some in my home-cooking. Made possible only last week when my aunt found some for me in a small packet instead of the usual big tins/bottles that I definitely won't be able to use up before their use-by date unless I'm cooking for an army.
These, on the chopping board, went into a fried rice with loads of minced garlic. Nyum! Going to tackle the steamed fish next. Wooooo!