i've seen that as well in my tank, the black and white clown sucks on the tentacles all the time and i've seen a few rbta tentacles laying around in my tank, glowing pinker than ever on the sand bed. that same clown also sucks on the frogspawn and duncans tentacles all the time now that i don't have a rbta. i see frogspawn tentacles on the glass to this day so i think its safe to say that in my case, maybe yours also, the black and white clown is responsible for this. it hasn't killed anything in the 2 or 3 years that ive had it though.