I have some cured live rock I purchased from my LFS
, and have had it sitting in a plastic tub with a powerhead for the past 4-5 days (to play it safe). I examined one of the pieces, and noticed a thin, brown spongy thing on the piece, which comes off after a light rub or scrape. The rock didn't smell funny or anything, but could that brown sponge be die-off, or is it part of the "live" stuff?
Just want to make sure before putting the rocks into my (already cycled) fish tank!