Come on, SOMEBODY must know more.

I'd expected dozens of posts about exactly which species to use, whether both halves make the same sound, how to get better tone by soaking them in whisky or urine, and a link to a Google Books version of a 1922 tutor on scallopshell playing in Guarani by the Paraguayan Ministry of Ocean Fisheries. Has nobody else here even heard of the idea?

(I play the washboard; scallops have a brighter sound but seem a bit more rhythmically limited. And they're fragile - the one first-hand description I've heard said there were splinters of shell flying everywhere in performance).