What is this??

[Jason R]

https://m.facebook.com/sharer.php?f...32673478338:mf_story_key.-6278343094027704135

I have had this stuff on my rocks for years. Does anyone know what it is??

 

[Jason R]

View attachment 9509here is a picture. The url above is to a video.

 

[Jason R]

[video=youtube_share;OArk1Auk_7Y]http://youtu.be/OArk1Auk_7Y[/video]

 

[Jason R]

I uploaded it to YouTube so it would be easier to view

 

[jrpark22000]

I would rule a sponge out. I can't say what type of algae or bacteria it would be though.

 

[Smitty]

Branching coraline?

 

[Jason R]

I haven't seen it grow longer than this. It is gray which isn't as easy to tell because of the actinic lighting.