The Numb Ray (Hypnos monopterygium), from the family Hypnidae, and order Torpediniformes, is seen occasionally in Sydney - both the day at night.
They are a really beautiful ray to see and are great at hiding in the sand. When they swim they look very graceful. Near their eyes they have some lures that help attract prey. In fact once I did not realise I was photographing a numb ray, I thought I was photographing some strange tube worms, until the whole sand around me moved and I realised I was right on top of a numb ray!
They include electric organs and can electrocute you if you scare them - so be careful! I know two friends who have experienced this and they both say it is very unpleasant!