Mysterious urchin death

[pleing1]

My verigated urchin has been really healthy and never shown signs of distress. It’s in a 300 gal invert only tank. No new animals introduced in 3 months.

Two days ago it released gametes. It looked totally normal yesterday. And then this morning I found it dead with 90% of its spines having fallen off in a circle. Ammonia and nitrites are 0, nitrates are 10. Salinity is always high in this tank at 38, but the animals have been in that for years. No signs of injury.

My initial thought is just old age? I don’t know how old this animal is as it was caught in the wild and been housed for a couple years.

 

[vetteguy53081]

In many cases, cause will be starvation, high phosphate or nitrate or temperature too warm
A few things to look at

 

[pleing1]

I'll check the phosphates, temperature was 77F, nitrates were 10. It's been eating normally except for yesterday. I just assumed it wasn't eating yesterday because of the stress from releasing gametes.