Nautilus pompilus , explicit and implicit versions. The 3D offset surface (left) and the convolved surface (right) are very similar.
The offset surface of this sea-weed is represented by cones and spheres (left). In the implicit form, spheres are removed and cones are replaced by line segments with linearly scaled field functions.
The offset surface and the convolved surface of an Unidentified Mollusk. The elements are pictured as cylinders to emphasize the spiral structure better.
The same tree skeleton as for the sea-weed, with "icing". 512 cylinders convolved with the trunk and branches, make a rather nice coral.
Superposition of two skeletons: the orange base and the spiral row of red horns (left) yield a smooth convolved shape of a new sea-shell (right). Does it look like a Cassis cornuta now? Of course it does.
The hand drawing (skeleton), the offset surface and the convolved shape of a sea-horse. Note how the wrinkles indicate the softness of the skin.
This is a very simple model. The skeleton of Spindle Cowrie is made of 3 arcs. Additional cylindrical spikes make the shape visually more interesting.
Trapezia rufopunctata (or just a coral crab). The simplified skeleton consists of 7 polygons (body), 26 arcs (limbs, claws and eye sockets) and 2 spheres (eyes). The convolved version has additional 608 cylindrical spikes, scattered along the surface. Possibly, the most interesting implicit model up to date. In the whole world :-)