Answer: Agate geode banding

What you're looking at

Agate geodes are hollow rocks lined with sparkling crystals and colourful bands of agate that you'd normally see sitting on shelves or in mineral collections. They come from all over the world and are prized by collectors for their natural beauty and geometric patterns.

This extreme close-up photo shows the intricate banding patterns that form the walls of a geode, revealing stripes of different colours and textures stacked like a geological cake. When zoomed in this tightly, the curved layers blend together into an abstract pattern that looks nothing like the recognisable geode you'd see at normal viewing distance, making it incredibly tricky to identify.

Look for repeating curved bands and layers with subtle colour variations, a telltale sign of agate striping.

How players did

4 players made 4 guesses. It took 3 guesses before someone got it right.