Can anyone tell me what my starfish was doing?

[pikastu]

I just saw this coming out of my Nardoa star. After leaving it for a bit, I checked on it and all its legs were retracted and it was curled and contorted so I assumed it died. I put in in a floating fry container to observe and now its walking around like it wasn't spilling its guts an hour ago? I know they're sensitive so I'm worried it might be an early sign of something wrong. I feed it a little bit of prawn whenever it comes to the top of the tank, usually 1-2 times a week. It doesn't always accept the food though.

Parameters
26c
Salinity 35ppt
PH 8.4
Alk 8.0 (have been slowly raising this after a drop to 6.5)
Cal 450
Mag 1300
PO 0.05
NO 0.25 (working on this as it was at zero)

 

[Reefing102]

Hmm almost looks like it’s excreting waste, but i can’t say I’ve seen a starfish do it in that manner before

 

[T Diddy]

It’s excreting waste. The anus of the starfish is in the center of its dorsal surface