Urchin spines
 

My long splined urchin died and behind a rock at that. I removed many stray spines from the tank after removing the poor guy but I'm wondering if I need to remove them all?

Won't have any ill effects to the tank. You removed the dead carcass, that's the main thing. If the spines bug you then yes get them out. If you don't care then leave it. All up to you

Thanks, I didn't know if by chance they'd foul the tank.

I'd suggest taking out as many as you can. My long spine has lost some spines over the years and I haven't taken them all out, and it doesn't seem to be hurting anything, but it's probably better if they aren't in the tank. If you have any sand critters (sand star) you definitely would want to take them out.