Is this algae or something else?

[tmerritt]

I’ve attached 4 pictures showing the stuff that is in question. I’m not sure if it’s all the same thing or not. There’s something green growing on the coral that flakes off. This stuff also grows on the rock, sand, and glass rapidly.

It seems like the growth has possibly killed some snails as they appear to be dead and I’ve read that some dinos can be toxic?

The tank was purchased used and in rough shape maintenance wise so I’m wondering if this could potentially be fueled by something in the rocks?

Please advise on what this and what steps need to be taken to resolve it. TIA!

 

[tmerritt]

I should add that the tank/rocks are many years old live rocks, but the tank was moved April 1st of this year (2022). So it’s almost 2 months at this point with no change in the rate of growth of this stuff.

 

[Chortanator]

Looks like green cyano to me. What are the nitrates and phosphates of the tank? As well as all the other parameters. It's not known to be toxic to my knowledge, but it can and will choke out corals.