A friend and I might have ruled out bryopsis. From the pics I've seen of bryopsis mine doesnt have leafy extensions from the stalk. Its just a straight strand. Cory, it's actually not "rough". Its fairly smooth and slippery (like that means anything). Unlike the hair algae I had, I can actually pinch one strand of it and it's almost crunchy. I mean, not like a burnt french fry but it definitely has some substance to it. I think it is fairly rooted because I have tried to pull it off the rocks and it tends to break off more than just let go. As you can see from the pics it's darker at the bottom but near the tips it's almost transparent. This pic is a small example of it. In my 30G it had completely taken over the the strands were at least 6-7 inches long. It looks like it was smothering my xenia, capnella and mushrooms. I wish I had taken a picture of that tank before I cleaned it out this weekend. It had been in my 30 for a couple months. I even took the rocks out and gave them a nice, close haircut hoping that it might die off....not real sure why it would. It just grew back until it got out of control. I'm wondering if it moved from my 30 to my 90 when I took a Colt leather out. It was growing at the base of the colt and I didnt want it to overtake it so I picked off what I could and put it in my 90. A couple weeks later, it's growing from random places in the rocks and sprouting in the sandbed. I did some housekeeping last night with a water change and sucked most of it out of the sandbed. I'm sure I could pull a good bit of it out of the rocks but trying to keep it all together and not have it float around my tank is next to impossible. I'm always afraid that a strand will catch a piece of rock and root itself there. Last thing I want is for it to spread even more. I'll take more pics of it tonight in different spots and post them. I did look through all the pics on the site you sent and there is nothing on there that looks quite like mine. I would have to say the closest thing to it by looks is Chaetomorpha aerea, possibly Cladophora prolifera (except not as dark). From what I've read on a couple different types of algae, some people say lettuce nudis will eat it up (like they did my hair algae) but they dont seem to be phasing it and at my last count I had 17 of them in there after a spawn. One guy likes to hang from the tips of it and dangle there but I'm not sure he is having Thanksgiving dinner.