A large turtle made out of iron, with chains so than a person could be restrained, spread-eagle across it's back. It was an instrument for the painful torture and death of heretics, designed by Vorbis during his brief rule as the 8th prophet of Omnia (before being terminally removed by his own god).
The Iron Turtle worked by a fire being lit underneath, until it slowly heated to roasting point, giving the condemned sinner chained to it's surface plenty of time to reflect. It was only ever used on Brutha (chained naked save for a loincloth to preserve his modesty*) before divine intervention put an end to its use.
- They were burning a man to death on a device of torture, but they had to preserve his modesty, you didn't know whether to laugh or cry.