pincushion urchin

Recently purchased two pincushion urchins from my lfs. Noticed one has pure white spines, while the other has black tips on its white spines. Is this normal, or do the black tips mean anything?

In the past, I’ve typically kept my refugium livestock free, only having macro algae in it. Right now however, it’s being overrun with green hair algae. You can see I literally have GHA growing on my chaeto. I was thinking about placing a Pincushin Urchin in there to clean up some of that...

I have two urchins in my main display, one tuxedo, and one pincushion. My tuxedo roams around the tank, showing up usually in a new location every morning. My pincushion on the other hand always is in the same spot on one of my rocks. I can clearly see that the pincushion has been exploring and...

https://photos.app.goo.gl/Zs2X3KTgtaPrgHAE7 I need help. I added this urchin yesterday after acclimating it and it was moving around really well and seemed fine. Come to this morning and it wasn't moving, I wondered if it was hungry so I put another algae pellet under by it, wouldn't move...

could i keep 2 pincushion urchins and 1 black longspine in a 75 gallon

Soooo I was watching my tank for a little bit while I was on my computer next to it and I noticed my pincushion sea urchin expelling tiny coco puffs from the back side of him. This is definitely a silly question, but I just want to make sure he is ok and that it's normal. I literally have never...

I've heard that pincushion and tuxedo urchins will starfish. Has anyone experienced that, or is it safe to keep both in the tank at the same time?