Long Spined Urchin turning white???

I have a black long spined urchin, who seems pretty healthy and happy he has grown a lot latly and is getting big! But 5 of his spines have started turning white. they are all even one on each side is that normal?? or is something wrong with him?? He moves around a lot but seems to spend most his time behind my live rock in the back of the tank.

 

hes been coming out more the last couple of days, and is getting really big, but Im still worried about these white spines

 

Is it a long spined sea urchin?? I have one of these and some of his spines have turned white in patches - i dont think its a problem cos i've had him ages and he's been like that since as far back as i can remember!

 

good that makes me feel better =) thanks

 

I am a active diver and I have seen a lot of long spined urchins with some with spines of spines that are partially colored white and black. I think it is some natural coloring, maybe something that develops when they get mature?