pencil urchin

Hi everyone, I've had a pencil urchin for just under a month and it was just dandy munching on clipped nori while I'm waiting for my ugly stage to kick in. When I first got it, it did lose a couple of spines but I chalked it up to stress from being a new environment. These past couple of...

Curious if anyone knows the species of this pencil urchin? I mostly want to confirm/deny if it’s a known coral or clam eater?

So I added a pencil urchin to my 29 gallon tank about a month ago and noticed right away that one of his spines looked wrong. It was much shorter than the others, red, and bulbous on the end with a hole in its tip that had a white protrusion in the center. I looked into this and couldn’t find...