How can you explain the low level of vital processes in terrestrial turtles? What are the features of the skeleton of turtles?

The low level of vital processes in terrestrial turtles is explained by the presence of a heavy protective bone shell in which, like in a box, the body of the tortoise is hidden. Due to the fusion with the bony shell of the spine (except for the cervical and part of the caudal) and ribs, the body of the tortoise is inactive. The chest, due to fusion with the bone shell, does not take part in the implementation of respiratory movements. Terrestrial turtles feed on plant food. All of the above led to a decrease in the level of vital processes in these animals.