Mystery Tan circles on glass??? ID help

[TriggerThis]

Ok these have appeared only in my overflow box so far, but they appear to be multiplying and growing in size.
There was one now there are 5 largest is the size of a nickel and increasing.
Need to know what it is and what to do about it. They look soft like a leather or something.
It is not a living animal. They do not move around. It is not a flat worm or a sponge.
Thanks.

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Sorry these are the best pics I could get, it is hard to get good pics of them.

 

[TriggerThis]

Bump

 

[TriggerThis]

I'll try to get better pics tonight

 

[Mike J.]

Well, I'm rarely stumped on a hitchhiker. I'll wait for a better pic. No clue so far.

 

[TriggerThis]

Ok got better pics

Just touched it with some tongs and it's really soft.

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I just want to make sure I don't spread it if it's some crazy bad invasive thing. It's deff growing though.

 

[Mike J.]

It's a sponge. Especially evident by the first picture with it's pourous composition. I'd say the beginnings of Liver Sponges.

 

[Reefing Madness]

Yea, now it looks like a Sponge. I've had those before.

 

[TriggerThis]

Liver sponges! I think that may be it
They deff look like livers