Who's mowing my (half) plate coral?

[DaFrog]

So, came home and so all the tentacles cut off! I suspected my big urchin and removed him (need to give him back to the LFS anyway as it ate all the algaes) - What could do it?
- Two clowns nesting five inches from it
- One Yellow watchman goby
- 3 Green Chromis
- One Mandarin
- One bicolor angel
- One yellow tang
- One (very shy) firefish
- Two skunk cleaner shrimps
- One Coral banded shrimp
- Two emerald crabs
- One pistol shrimp (nest two feet away)
- Red and blue leg hermits
- Nassarius snails
- Two sifting seastars
- Way too many brittle stars
- Copepods + amphipods
- 75 gallons
- All water parameters good as of yesterday
- More tank details at http://www.percula.net/?cat=2

 

[Anonymous]

I think the bicolor could be a likely candidate

 

[bfessler]

I agree. I observed a bicolor in a friends tank making a meal out of LPS.

 

[Anonymous]

What's you tank parameters? That looks like recession to me due to low MG or ALK levels. Reason I say that is the LPS still has polyp extension. What do the other corals look like?

 

[DaFrog]

I will retest alk later today - Other LPS (frogspawn and pearl) look good: