Aloha Keith, I've been noticing this for years off the Waianae coast of Oahu. Insularum seem to "herd" from Oct-Jan. I know they migrate from deeper waters. This was surmised by the thick orange sponge growth. The longer the egg-laying process continues the external sponge covering starts dissolving from exposure to higher levels of UV light. By the time they start to leave no sponge is evident. This species prefer the first major reef drops connecting to open sandy streaches that drop fast to deeper waters(usually 70-90ft). Divers off Kauai have noticed this as well. Sometimes you might chance upon a dead Porites coral head covered in purple egg clusters. Means the mamas have already left. It's good not to reveal these locations as insularum tend to frequent the same spots as the previous years. Last dive partner i showed this to wiped-out the whole massive colony. CHRIS:) ---------------------------------------------------------------------- [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. ----------------------------------------------------------------------