Sydney's Pygmy Pipehorse
Similar to its common seahorse relatives, the Sydney's Pygmy Pipehorse has a long prehensile tail, large head, compared to its body, and tall frontal ridge. Unlike the Sydney's White Seahorse which can be up to 20cm in length, the pygmy pipehorse is much smaller and can only grow up to about 5cm. It has white to grey colour or red with brown blotches or sometime with bands. I haven't yet seen those with bands or white colour.
Endemic to Australian temperate waters of the east coast. They can usually be found in semi-exposed algea covered reefs. I found the one in the photos at 20m depth. Around Sydney, they can often be found by enthusiastic (not male egos!) divers at Kurnell and Bare Island.