Black spots in my sump..any idea what they are?
 

Over the past few days, have had dime size black spots all thru my sump as per pic.......are these an indication od something sinister? They appear to rub off easily.

Please advise.

some kind of spunge I would say.
what texture does it have?
does it react to the touch?

Bill

Just rubs off, but they are doxens of them through-out the sump
 

Could be related to the pinnacle shaped black 'sponges' that have been growing in the tank for the past six months. I pull it out of the tank regularly.

Also, if I do remove them just by wiping them off.....
 

should I leave all the other beings as they are. Are they all beneficial?

yep, as far as I know most of the stuff that grows in your sump is beneficial until they get to a heavy load on pumps, skimmers etc. Then I just either scrape them off or soak in vinegar.