Is this a hairline scratch or silicone from manufacturing?

[Sean999]

Hi,

I picked up a new Aqueon column 15 fish tank from Petsmart and I was wondering if this defect on the bottom of my fish tank is normal. I am not sure whether this is a hairline crack or if it’s silicone residue from manufacturing. It is only felt from the inside and not on the outside. Please let me know what you think.

 

[bill.marshall]

might be some silicone..try scraping it off, with fingernail, does it feel like rubber.