Marcus, If the snail replaced the shell from the inside as the outside was eroded, it could end up moving the suture line. Allen Aigen [log in to unmask] -- Marcus Coltro <[log in to unmask]> wrote: Hi Andrew Yes, no doubt it is eroded, but I can't quite understand the dislocation of the line as it was melted. If you grind a shell it will not look like this, the shoulder line will not be displaced. Marcus Hi Marcus The shell has been severely eroded on tle lower surface. I think this will be because the animal was geronitic and had stopped growing, hence the shell has been exposed to abrasion on the final underside (remember the shell rotates around the coiling axis as it grows, but ceases rotation at cessation of growth) long-term. I have noted a smooth eroded patch behind the aperture in a number of largish Recent & fossil operculate shells (eg Penion, Pleuroploca)... these specimens had ceased growth and the shell had become worn where it rested on the operculum during the snail's activities. -- Andrew Grebneff Dunedin New Zealand Fossil preparator <[log in to unmask]> Seashell, Macintosh, VW/Toyota van nut No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.5.476 / Virus Database: 269.10.4/897 - Release Date: 11/7/2007 21:57 ---------------------------------------------------------------------- [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. ----------------------------------------------------------------------