Within hours of fertilisation the eggs develop into free swimming planktonic larvae. The larvae swim in esturine and coastal waters for up to 3 weeks during which time they develop transparent shells and a retractable foot. The larvae then settle on a clean substrate using the foot to find a suitable site. The foot is resorbed once the larva is attached. The shell darkens and the small animal takes on the appearance of an adult oyster.
Growth rates vary with local conditions.
Sydney Rock oysters change sex during life. They start out as males and later change to females. They are filter feeders, straining planktonic algae from the water. They are prey to a variety of fish, including stingrays, mud crabs, whelks and starfish. There is no commercial harvesting of wild Sydney Rock Oysters.