Longspine urchin eating zoas

[gregzz4]

A couple weeks ago my Flaming Sun zoas started melting/shrivelling/vanishing. No pests spotted.
Then a few days later whatever was going on had spread to my nearby Watermelons.
I pulled out and dissected some closed polyps but found nothing.
A week passes by and I catch my longspine in the watermelon colony but figured it was only cleaning the newly exposed LR.
This morning I look and see my Lemon Drops are gone, and the urchin is sitting on top of my LA Lakers. I pushed him off and all but 3 polyps are gone

Needless to say the urchin is now residing @ J&L, although I felt like putting it down the garberator

I'm back to Strawberry Tophats