I forwarded your image to Lindsey Groves, our museum's collection manager of molluscs. Here's his response:
"Definitely not an Opalia (FYI, O. chacei has been synonymized with O. borealis). It is most likelyEpitonium montereyensis, which Jim called E. indianorum in the Light’s Manual revision in 2007 (pl. 367E). Epitonium tinctum would be a best second best guess. The tiny specimen to the left of the large epitoniid is too small to id from this image. Hope this helps."
Jim is Jim McLean, the museum's curator emeritus of molluscs