small black spots on glass

i noticed a bunch of small translucent black almost purple spots on the glass tonight? inot sure if its algae or not??????

any ideas??? spots are about 1-2mm in width

 

If its purple could be coralline.. I havent seen black before.. A pic would help.. Im staying posted to see what others say too..

 

Maybe blue green algae.. AKA cyno??
http://www.3reef.com/forums/algae/ultimate-nuisance-algae-thread-58657.html
You may find it hear..

 

tired to take a pic, not sure if you will be able to see them. Thought maybe coralline untill i was able to wipe them off with a mag float. Not sure but i didn't think you could just wipe coralline away even with such a small spot. i have had a large growth spurt over the last 3 weeks of red and purple coralline on my rocks. your right, maybe it is some sort of cyno (thought i was finally done with that )

 

opps, sorry. here is the pic