They are a false fire urchin (astropyga radiata) and a commensal zebra crab (zebrida adamsii). Really really neat. The urchin has some crazy color and is amazingly active while the crab just hangs on to the spines with a pair of specialized rear legs and just orbits around. From what I've read it's mostly a one-way relationship - the crab gets protection from the urchin and reaches whatever crumbs are nearby and possibly also eating the spines themselves but not enough to kill it. The crab is also known to jump from one host urchin to another, so it'll be interesting to see if it takes to my longspine as well. Funny thing is I guess the urchin's part of my clean up crew, but he's also by far the most colorful thing I've got in the tank, so he's kinda like a janitor in tails and a top hat [smilie=lol.gif]
Haven't been able to get good pics yet, but here are a couple of iphone pics[attachment=2]New Urchin and Crab 2.jpg[/attachment][attachment=0]New Urchin and Crab.jpg[/attachment]
Here is a professional image of a MUCH bigger urchin: [attachment=1]zebra-crab-zebrida-adamsii-in-symbiosis-with-an-astropyga-radiata-sea-urchin.jpg[/attachment]
Haven't been able to get good pics yet, but here are a couple of iphone pics[attachment=2]New Urchin and Crab 2.jpg[/attachment][attachment=0]New Urchin and Crab.jpg[/attachment]
Here is a professional image of a MUCH bigger urchin: [attachment=1]zebra-crab-zebrida-adamsii-in-symbiosis-with-an-astropyga-radiata-sea-urchin.jpg[/attachment]