I have had this since I bought these mushroom coral. This patch looks just like fruit mold. That's the best way I can describe it. It has what look like micro-feather dusters coming out of it which are covered in a gel and it's light blue/gray and the outer gel is transparent. It doesn't wave much with the moderate current that passes over it and appears to be growing steadily but rather slowly.
Any guesses?
Standard crop:
Any guesses?
Standard crop: