Soft Spongy Thing on the rock

[rahul123]

Some soft spongy thing started appearing in my 2.5 year old FOWLR tank's rock suddenly. I have not added any new thing since past one year.
Can anyone help what the thing is - good / bad?

 

[EeyoreIsMySpiritAnimal]

If you're asking about the red stuff, it looks like cyano.

 

[crazyfishmom]

Agree that this is likely cyano.