Hi, I'm new to this group and to conchology. I have a burning question, unanswered by lots of googling, related to a 11-cm specimen that I collected while snorkelling last week in Puerto Rico. It looks like it could be Cassis tuberosa. The shell appears to have grown in stages. A distinct bi-lateral lip is formed, creating a flattened surface at the aperture. Then the shell is extended two-thirds around the spiral and another lip structure is formed, against one side of the former lip. This appears to have happened at least six times in the life of my specimen. So my question is: How does the animal do this? What does the shell look like between the lipped forms, and how does the animal live? Further confounding my understanding is the existance of an upturned "tail" on the end opposite the spiral face. That structure could not continue to grow in a self-similar fashion. So is it simply encased in the subsequent growth cycle, along with other protuberances? The shell almost doubles in diameter with each cycle. So the amount of material that must be added in each cycle must be at least equal to the mass of shell that existed. Does that mean that there is a final determinate state beyond which growth is not possible -- leading to my finding of this empty shell? Thanks in advance for satisfying my curiosity! ---------------------------------------------------------------------- [log in to unmask] - a forum for informal discussions on molluscs To leave this list, click on the following web link: http://listserv.uga.edu/cgi-bin/wa?SUBED1=conch-l&A=1 Type your email address and name in the appropriate box and click leave the list. ----------------------------------------------------------------------