The Mathematical Study of Mollusk Shells
Nautilus. 
Astroceras. v=.12, c=1, a=1.25, b=1.25, h=3.5, k=0, t=40..1

Euhoplites. v=.1626, c=1, a=0.6, b=0.4, h=0.9, k=0, t=40..1 
Bellerophina. v=.06, c=1, a=0.85, b=1.2, h=0.75, k=0, t=10..1 