Several nautical miles offshore, a special diving boat is a mere speck in Port Phillip Bay. Key points: Marine scientists are rebuilding reefs using recycled scallop and oyster shells from restaurants. The project has built 12 hectares of artificial reefs in Port Phillip Bay out of a planned 100 hectares. A crucial part of the restoration project has been producing the angasi or native oyster. The bay, comprising almost 2,000 square kilometres, fans southwards from Melbourne, Australia’s second-biggest city. Two divers carrying live shellfish are descending on an artificial reef, taking another small step in an ambitious reef restoration project — the largest yet undertaken in Australia. Known as Reef Builder, it is backed by federal and state governments and overseen by The Nature Conservancy. “Our Commonwealth investment has produced 40 hectares of shellfish reefs, and it’s a truly fantastic program,” Environment Minister Sussan Ley said.