This is a photo of a sulcata tortoise’s plastron (lower shell). This was taken just prior to surgery. Dr. Mertz was fixing an intussusception, or a condition where one part of the tortoise’s intestines had slid into an adjacent part, causing a telescoping effect that blocked food from passing through. It’s difficult to perform surgery on a turtle due to the hard shell. Cutting out a piece completely cuts it off from any blood supply, and the piece of shell will die and not regrow. In order to allow the shell to heal after the procedure, Dr. Mertz essentially cut a window, as you can see in this photo. Three sides were fully cut, but the fourth just had holes drilled into it so it could be lifted up without being fully detached. This let him perform surgery while still allowing the shell to heal afterwards.