Should I ask what this Urchin is doing?

[dg3147]

So, I turn on my light to see how the tank is doing and I think I caught my Tuxedo in an obscene solo act. It is upside down from it's normal position (the hat that he normally wears consisting of snaills, hermits, algae, the the occcasional mushroom polpy that he usually wears on top is now on the bottom). Below is the pic with him apparently spewing white...we'll call in "smoke" up into the tank current.

 

[dg3147]

...I think I'm gonna run some chrcoal ---my tanks seem so...so....so "dirty":lmao:

 

[Bongo Shrimp]

My guess is spawning.

 

[KarmaChameleon]

My urchin seems to do this every time I do a large water change with slightly cooler water . I feel a little sorry that he doesn't have a mate.