I received an email that had pictures headed 'strange oyster'?

But I don't think it's an oyster and would like to know what exactly it is. The shell is maybe 6 inches by 4 inches, approximately oval and a bivalve, gray or silver in color. The strange part is the protruding 'tube' of flesh that to be honest has some resemblance to a giant male varying in length between 8 and 20 inches and about 2-2.5 inches across. Very weird. Pictures have fishermen and women with a large catch of these. Any further information would be most helpful