Organic shape

Got asked how I modelled an organic form, so I uploaded the pictures here.

First I started with a box and a smaller one inside it

Then I deleted the other faces and 'bridged' it to the inner box.

As the shape is symmetrical, the symmetry modifier can be used instead of going though each one.

 Used the squeeze modifier

 Shelled it to give thickness

 Mesh-smoothed it

After this I just played around with symmetry and FFD