Hi there,
I came across your question whilst doing some research. (I'm writing a dissertation on polychaete infaunal interactions in thailand).
There are many families of worms from which your example could come from. The 'tentacles' are not individual worms but the feeding apparatus of one individual worm. Perhaps you have a terebellid worm, they typically have more 'tentacles' but there are many many possible different taxa.
here is a terebellid worm showing all its tentacles, is this what you have? http://depts.washington.edu/fhl/zoo432/falsebay/fbfeeding/terebellid1.jpg
These filter feeding worms feed by trapping floating particles and entraining them in mucus before sucking the mucous in a continuous string into the mouth, the reason such a large amount of detritus occurs is that while we can choose what food we put into our mouths the worms cannot. Much of their food is in the form of a biofilm around, for instance, a tiny grain of sand. They suck the biofilm off and the rest of the particle is excreted, or sometimes there is no food and its just a floating particle. Either way, they will capture everything that floats past them, food or not, and excrete it.
Although our anatomy is not equipped for eating sand-imagine how much sand you would have to eat to sustain yourself on the organic products that are present on each grain. Look on the bright side- he's picking up your filters slack!
