The Big Pterodactyl

Thunderbird Park sits on Tamborine Mountain in the Gold Coast hinterland, and its long-standing attraction is thundereggs: volcanic geodes, dull grey lumps on the outside, that split open to reveal crystalline agate. The park is one of the few places in the world where visitors can dig their own and have them cut on site. The name comes from the thunderegg, and the thunderegg's name comes from a legend attributed to Native American tradition about thunder spirits hurling the stones – which is where the park's whole visual identity, thunderbird and prehistoric creature alike, originates.

A pterodactyl is not a dinosaur, and it has nothing to do with thundereggs, which form in volcanic rhyolite. The connection is atmosphere rather than accuracy: ancient, geological, faintly prehistoric, the impression a place full of rock and forest wants to make.

The orange is a good decision. In dense subtropical rainforest greenery, an orange object is visible from a distance in a way that no naturalistic colour would be.

On the dimensions, what it is made from, the installation date or any attribution, the record is silent.