It means "they already debunked the theory that that could be Atlantis and those lines were photographic errors caused by boating paths or some such thing."
* chocolate-neko 's sing-along blog: Seu Jorge ·· Queen Bitch [00:26<03:42] <chocolate-neko> shad sent me this <chocolate-neko> it sounds like a mistake <chocolate-neko> also he thought he sang in French <chocolate-neko> what a shad
Yeah, it was a before yesterday. Thanks! Is that shark wearing a hat with another shark on it? Because that's what it looks like. Also you're getting pretty good at drawing sharks on Muro.