Do you know what is this? Pics

[r2d2]

Hi, yesterday I was changing water and notice some kind of algae loosing from my LR so I scratch it with siphone and for my surprise not only red algae get loose but also a thick layer of LR. I dont know if that is dust or actual LR.
Here you have some pics...



Here is some still attached to LR, is like flufy..





My tank has this kind of algae in many places is dark red color.
By the way, here is a general view of what I get in 6 months.



Thanks.

[reefjitsu]

These mats are a mixture of sediment, detritus, cyanobacteria, algae and other microbes. You should be able to siphon most of it out when you do water changes. Incedentally, these microbial and sedimentary assemblages are pretty much the same as the process that forms stromatolites. Fossils of this nature are among the oldest records we have for life on Earth.