Thank you for waiting. Shipped reptiles do often arrive in less than perfect shape. That knob could be the result of an injury that caused some swelling. However, such swelling can also be the result of early Metabolic Bone Disease (MBD. It's possible the seller didn't have a UVB light on him, or wasn't providing calcium. If there is a minor injury, the swelling should go down in a day or two. If it's MBD, it can be reversed over a period of weeks by providing UVB light and calcium. I realize many pet stores and even breeders recommend calcium with D3 in it, but I strongly prefer plain calcium with a good UVB light (so the body can make its own D). Supplementing with D3 can cause kidney disease and neurological disorders. Kidney disease caused by too much D3 can lead to deposits of uric acid in the joints, causing swelling and mobility problems. You can read more about D3 and kidney disease here:
If you can't find plain calcium locally, here is an online source:
While it doesn't have anything to do with the knob, I do recommend that you adjust your temperatures a little.
Chameleons are adaptable to temperature extremes in their wild habitat, but there they can move around to find warmer or cooler spots. In a cage they have no choice. The coldest part of the cage should be 82.5*F. There should be a warm basking area that is kept at 89*F to 113*F. That sounds hot to us, but to a chameleon, it is just right. At night the temperature can be allowed to drop to 72*F to 79*F. Use a good digital probe thermometer to measure the temperature. You can adjust the temperature by raising or lowering the fixture or by changing the bulb to one with higher or lower wattage. If you have to lower the fixture, don't put it so low that your chameleon can touch it and be burned.
You may also want to consider having a reptile vet examine this little guy. the vet could actually feel that knob and perhaps x-ray it to find out exactly what is going on in there. It's a good idea to have any new lizard examined soon after purchase anyway, but when there's any kind of symptom, it's even more important. If you don't already ahve a vet, this link will take you to a directory of reptile vets:
If you have more questions, let me know in a REPLY. I hope Benny will thrive for you.
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