The Black Pearl Oyster or Black Pearl King Oyster is a oyster mushroom (Pleurotus ostreatus) hybrid from Japan. It is the result of a cross between a European and an Asian Pleurotus ostreatus. It grows and looks much like Pleurotus eryngii (King Oyster) in the beginning as it matures it will look more like a Pleurotus ostreatus (Pearl Oyster). Black Pearl Kings are less finicky than Pleurotus eryngii, and are able to grow very well indoors. Grows on the same substrates as pearl or king oysters such as masters mix or hardwood sawdust (HWFP). It is a fast substrate colonizer that fruits dense, meaty mushrooms.