Examples: Cephalopods: adding ridges
Argonauta (helmet shape, [2, p. 249])
[alpha=80, beta=90, phi=0, mu=0, Omega=0, A=2, a=2, b=1.5, L=0.3, W[1]=150, W[2]=20, P=5, N=30]
(Click with the mouse over the picture to rotate it)
The so-called shells of the argonauts are, indeed, nothing more than the calcareous secretions made by the
females of octopuslike mollusks which lack true shells. Used to hold eggs, they are discarded once the eggs have hatched out.
The shell is thin, fragile and inflated, with widely spaced, radiating ribs ending at the periphery.
Habitat: free swimming, occur worldwide in warm seas.
[2] S. Peter Dance, Shells, Dorling Kindersley, 2002.
