Numb Ray
These rays are unique to Australia and are called Numb Rays for a very good reason - if you accidentally touch one, you'll get a powerful electric shock and your arm will go numb. We know... we accidentally touched this one when it was hiding under the sand.
They can get quite large (over half a metre across) and have expandable mouths so they are able to electrocute large prey such as penguins and eat them whole.
Numb Rays are also known as Coffin Rays (just to emphasise the danger), so it probably goes without saying that it is best to avoid touching them.