If you like unusual cacti how about this Mexican one, Pelecyphora aselliformis? The Generic name means "hatchet or axe bearing" and the specific one "like a wood louse".
I have not yet got around to a macro picture of the tubercle ends so here is a blown up crop of part of the the above picture, hence the poor quality which I apologize for, just to show the ends of the axe shaped tubercles more clearly with their elongated areole and small pectinate spines that look like wood lice on their backs, hence the name.
Earlier images, not yet re-categorized. All subject types. Not for new images.