This is getting bizarre, when I caught them out their old tank I did not see these growths so thought it had just skipped by attention somehow.  I first noticed the growths when I caught them out a white drip in bucket drip and put them into their new tank. I dosed the new tank with Herbtana and when I looked at the shrimp the next day I failed to find one with any such growth.. I dosed for the next two days as a precaution, but have yet to find any trace of these mystery spots..   Baffled