A VERY great white shark (made of LEGO). There is a new exhibition just opened at the Sydney Aquarium for the next 12 months called On The Loose. Link to minisite is here: On The Loose exhibition
Australia's own LEGO Certified Professional (Ryan McNaught) went to Sydney to help with the installation, and has posted a series of behind-the-scenes photos up on Flickr at this link: flickr photos from ryan mcnaught