6"x4" very thin shell. From Corny Point, South Australia - soemthing about these washing up only once in seven years?!?! is the only info i have
[url]http://www.badongo.com/pic/5129979[url]
It is the shell of the common paper nautilus, <i>Argonauta argo</i>. It is in fact not a shell at all, it is the empty egg case of an octopus relative. The female nautilus constructs this shell from two modified arms to carry herself and eggs to keep them safe from predators. The male is a tiny squid like creature. Once the eggs have hatched the shell is discarded. You are lucky to find one in such good condition, they are usually smashed to pieces when they wash up onshore. A very nice find.
Dave
Actually this appears to be the closely related Argonauta nodosa, the Nodose Paper Nautilus, an even rarer find.
Many thanks gentlemen.
         Peter
I think you are right Paul, I am not that familiar with this family.
Dave