Sick urchin

[oool8899]

This guy developed this black spot felt like over night. I've had him in the tank for a while since and he has moved somewhat normally but that spot has continued to die, he used to have needles and feet on it like normal. Is this a disease or damage from a sting or something else?

 

[fishywishy]

Maybe burn damage from a heater?

 

[oool8899]

No heater in proximity to tank it's in a sump, he was in a tank with a larger aptasia that was hiding before I moved him so my initial theory is sting but I'm not sure