@Reefahholic have any of the pieces you've treated also had any feather dusters on them and if so, did they survive treatment? interesting note, after treating this torch I have, all of the spionids appear to be dead. certainly no tell tale antennae sticking out. however I did notice a feather duster that was on the side that had survived today as it peeked its crown out. I used the same dosage you did (if anything a bit stronger) and agitated for over an hour. I definitely have some remains here that clearly were boring polychaetes but I certainly would have expected a feather duster to also have died