Is this tissue necrosis?

[Asian Hurricane]

Hi, I am starting to get into SPS and I just bought a frag from a local fish store. I just noticed white at the bottom and I am not sure what it is. I was hoping y’all could educate me. Thanks!

 

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It does look like the start of it. If it were me I would cover that area with glue. This often can stop it from continuing.