-Its a callused plant material and flesh compound that's lightweight and has the texture of porcelain. Its about as strong as you'd expect from it being half an inch thick in places. The hardness makes it hard to cut or stab through (but with enough force, it gets the job done). The blunt damage is simply about smashing as much of the shell as possible and burning away the core material by exposing it to light.
-The organs exist, but they don't do much since the matter does mostly everything. I could go into detail but I'd rather clap my hands and yell "Nazi Mysticism". Since explaining chemical interactions within the liver as it reacts to oxygen sounds fun.

EDIT: Fancied up the profile in tiny bits. idk how much easier it is to understand.