Creating a shell shape

[rubyred67]

I need to create a shell, not sure where to start creating concave shapes, any recommendations would be great.

[rubyred67]

Is it just a question of moving the editable poly's verticees?

[Cad64]

There are many ways to make a shell, depending on what type of shape you require.
So, what type of shell are you making? Can you post an image?