Shell growth in the cowry shell Mauritia arabica, from juvenile stage (upper left) to adult stage (lower right).
Picture: Denis W. Riek.
Shell growth in the cowry shell Mauritia arabica, from juvenile stage (upper
left) to adult stage (lower right).
Picture:
Denis W. Riek.
The shell of cowry shells (Cypraeidae) develops until reaching the adult stage. Juvenile cowries at first have a shell with a clearly distinguishable spire, which is referred to as the Bulla stage, since it resembles the shell of a bubble snail (Bullidae). With the snail advancing in age the outer, newer shell whorls grow over the older ones, until the whole spire dissappears in the shell's interior, so it starts to take the characteristic cowry shell shape.