The web sounds normal to me from what describe. Chiles are notorious for not eating for months on end and staying in one place for hours or days on end too so they get called rocks LOL. If she has a hide in the tank and she is about to moult chances are she'd web herself in her hide. Mine has a dark spot just where the carapace joins the abdomen but she's had that ever since I've had her. The abdomen will really swell up and look much too big for her before she moults.

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