Pincushion Urchin eating Chrysophytes?

[TinyChocobo]

So I have what has been identified under the microscope as a chrysophyte bloom in my tank. It's a relatively new setup - about 2.5 months.

The chrysophytes have completely covered one rock and have started spreading to a few others a little at a time. I do also have some red cyano.

Just when I was about to do something about the chrysophytes - siphon+water change + GFO + black-out - I found my pincushion urchin munching and clearing large swaths of the chrysophytes.

Anybody else had an experience like this? They have been in the tank for a while and he hasn't touched them until today... Not until I actually went to go get a picture of my apparent chrysophyte farm only to find him sitting right in the middle and a lot of the chrysophytes missing.

 

[nautical_nathaniel]

Urchin are algae eaters, so while I'm not super surprised that yours took a liking to them, it is sort of surprising that it took it a moment to go after them. My black shortspine absolutely destroys any patches of algae I get to grow in my tank (good and bad, except for bryopsis, but I took care of that through other means). Mine will usually work on a patch of coralline for a few days if it hasn't been to that side of the tank in a while, so maybe that's what was going on and it needed to finish up some other stuff before going after the chrysophytes.

 

[TinyChocobo]

He's all over the tank on a regular basis but he has been eating on the sheets of nori I put in there for the tangs. No matter where I put it - he finds it and munches on it.