To me, the facinating thing about Xenophora and their attachments as a
disguise in Guaymas, Mexico was the fact that most of them had a
complete covering of grassy algae that hid everything.  To find them you
looked for lumps of algae.
 
The same thing applies to other schemes that are generally taken as
camouflage:  If it is a disguise, why cover it up with something
entirely different?
 
Aloha,
 
Wes