The variable thickness of the outline looks a bit sloppy, as well as the absent aa on interior of said outline. It’s strange that the cap of the mushroom has a very dark outline, while the stalk has none at all. The light source is a bit all over the place, it seems to be from above on the eyes but from below on the neck. The iris and pupils could also be a bit more round, they’re a bit wonky atm. The problem with the shell is that you focused on defining the individual segments instead of the general volumes (by shading the planes of the shell according to the light source)
Cure, thanks for the critics, I corrected most of them.