what is this mushy thing?

[reef tank 2.0]

over the past month, I've noticed a tanish mushy blob on the walls of my stock tank. while looking around the tank tonight, I looked at the overflow, and noticed that the blobs are there too. although I didn't touch these things with my hands, I scraped one off in the sump, and noticed it was definitely soft. I don't recall ever seeing one of these before.
in the sump, these things are on the walls, as well as everything in the sump. they are roughly 1/4"-1/2" in diameter. they don't move all all. almost like algae of some sort. but these are in areas of the tank that get no light

here's a picture of the back side

 

[EeyoreIsMySpiritAnimal]

Sponge

 

[reef tank 2.0]

good, bad, or neutral? where did it come from? there is nothing in my sump that came from another persons tank,

 

[reef tank 2.0]

are these good, bad, or neutral?

 

[SudzFD]

If it’s a sponge it’s good. Filters nitrates out and other stuff. Consider yourself lucky.

 

[BristleWormHater]

are these good, bad, or neutral?

Good/neutral

 

[reef tank 2.0]

@SudzFD - lucky, why? are these not a common thing that all reefers get?

 

[PharmrJohn]

I didn't have any of these that I noticed in my last tank. Hoping for some with my next!

 

[reef tank 2.0]

If they are not "common", where did they come from? They are only in the sump, and well, in the overflow. All dark places. My sump looks like it has polkadots everywhere

 

[phillyb614]

If they are not "common", where did they come from? They are only in the sump, and well, in the overflow. All dark places. My sump looks like it has polkadots everywhere

Likely rode in on a coral or a piece of live rock.