Hi James,
Slit Shell Site - that's a good tongue twister.  Don't try to say it five
times fast :-)
Not as difficult as Bug's Black Blood, but still a challenge.
If you want the pictures of Perotrochus westralis I used in Bret's recent
auction, I'll be glad to send them to you.  They are not of the living animal,
but show the shell quite nicely.
Regards,
Paul