Acropora feeding response.

Any one heard of Mesentry Filaments?
I have seen these white filaments coming out of some of the acros in my
tank.
These are very thin (0.1mm dia) and up to 15mm in length most are pretty
short though 5mm or less.
they seem most prevelant after plankton replacement (Golden Pearls in
this case) is added to the tank.
Are these things feeding the coral or what?
Does the coral pull the strand back into itself and strip the excess
particles for food something like a vernetid snail?
Or are they looking for the source of the irritation and/or a possible
fight with another coral?
Thanks for any info
Simon