The shell itself is made from broadened and flattened ribs, fused to parts of the turtle's backbone (so that unlike in cartoons, you couldn't pull a turtle out of its shell). The shoulder blades sit underneath this bony case, effectively lying within the turtle's ribcage. In all other back-boned animals, whose shoulder blades sit outside their ribs (think of your own back for a start). The turtle's torso muscles are even more bizarrely arranged.
Ed Yong looks at turtle anatomy and how this weird configuration evolved from the basic vertebrate plan. Link
the above just explains why coz even if i was a kid back then, it seemed to me like its skin is attached and pulling it out would hurt the being (if it's still alive)