Help ID’ing “ring” around toadstool leather

[Quip]

Noticed this “ring” around our Toadstool leather. We’ve had it since July of last year and seems to be growing vertical pretty rapidly. 
 

Water levels are all fine. Any idea what that “ring” could be? 
 

Thanks in advance. 

[Opotter]

I’m definitely not an expert, but my first thought is hair tourniquet.  Which is not a reef thing by any means.  I’m in the medical field and we see little kids come into the ER sometimes with a piece of mom’s hair wrapped tightly in a little fold of a finger for example.  Looks really similar, but maybe just my irrelevant life experiences.. lol.   Any chance you have long hair that falls into tank sometimes like mine does??  Could it be wrapped around that toad if you look close?  Or dogs/cats that get hair in the tank?

[Christopher Marks]

@Quip your toadstool leather may be beginning to split itself, they are known to self propagate, not always in expected ways. 🙂 

[Joevember]

Like CM said it could be it latitidinal fission. Some anemone species split like that, but never seen a toadstool do that. 

Has it shed recently?