Rounded spines

I haven't had a chance to post this mystery close-up photo.  Do you recognize what animal this is?

 

Below is an expanded view.  Perhaps it will start to look more familiar?

 

These are close-ups of the spines of an Ochre Sea Star (Pisaster ochraceus).  The spines are made of calcium carbonate and are external projections of the sea star's internal skeleton.  Most of the time, we're used to seeing the spines from farther away, scattered across the surface of the sea star:

 

It's fun to see what the spines look like up close!