Added base with small support podium in center
Cropped and obscured screenshot demonstrating the complete lack of distortion to the right side of the crab

Distortion was initially accomplished using a cage edit in conjunction with other tools, however due to crashing problems the cage edit was swapped with a lattice distortion in Blender 2.8, which is near identical to the cage edit function in Rhino, while fine tuning, solidifying, and other tweaks were accomplished in Meshmixer

 
 

 
 
 
 
 
Model after initial deformation work, note that front claws are now very similar in size
(Original model before deformation)