Dan Monceaux, a local member of the Marine Life Society, dived around the Torrens Island jetty and made lots of observations that he’s shared on iNaturalist, including seagrass, sponges, razorfish, flathead, bream, goby and most pleasing of all some native oysters (Ostrea angasi).
The native oysters were found at approx 3.5m on a mid tide and estimated size was minimum 6-7cm diameter.