Push back, arching your spine into a convex shape, then reversing it into a concave position.

Computing the convex hull means constructing an unambiguous, efficient representation of the required convex shape.

The cap has a diameter of 4to10cmin 1, and has a broadly convex shape when young, but eventually flattens.

It has a campanulate (like a bell) to convex shape, later becoming flattened, with a very blunt umbo.

It has a convex shape, but splits at the margins.