spiral staircase leading down.
The intrepid Muko led the way down the stairs, the others following. They were now under the courtyard but there was something wrong. Looking up, they could see the artefact through the ceiling as if the floor of the courtyard were made of glass. And yet when they'd been above looking down, the floor had been solid rock. They looked into the chamber ahead of them and saw a whole load of different mathematical symbols and what looked like … skulls. Suddenly they were very frightened. Paidia held on tightly to Gelio.