Wondering what this small dark tube with white spikes is. I found it on top of my sand bed today in my 20g reef tank. It wasn’t alive and was pretty brittle when I picked it up with tweezers. Pretty small, you can see it in relation to the tips of a small pair of tweezers in the pics. Almost looks like something from an urchin, but I haven’t had any urchins in the tank. Guess it could have just came in the bag of sand I used to start the tank several years ago and I just noticed it today.
