Thin White Filaments

[tlhood]

So I noticed yesterday that on the underside of my Leptoseris there were these weird white filaments blowing around, maybe 6 or 7 of them. They looked like they were attached to the coral. Today, I couldn't see any. However now on my baby fungia-type coral, I noticed there are two of the weird long filaments coming from the underside and blowing around, and there are some smaller ones looped on the top side. Anyone have any idea what this is?

Nothing has changed in my tank, my last water change was on Sunday. I have noticed quite a few amphipods and little worms (I think they are bristle worms) at night, but none on these particular corals, they usually stay on the rocks. I am fighting a nasty algae outbreak, but that's been going on for a while and this hasn't happened before.

I snapped a picture with my phone. You can really see the one that's in the back, the other ones are tougher. I had just turned the lights on so the edges of the coral aren't as open as usual, and I'm keeping an eye on it to see if it fully extends like normal. The corals have been in my tank since the end of January, and have shown some considerable growth.