Blue Xenia missing

[pulik]

Water parameters are acceptable, other than nitrates are a bit high at ~10, and kH a bit low at 161.

It's basically a Nano reef (~41 gallons), with only a Coral Beauty in the Angel family; could she be a problem? Haven't noticed her picking on anything though - and this did happen during the night... I have a Peppermint shrimp and a Pompom crab besides a few Blue Legged Hermits (along with a swack of hitchhikers); so you think the Peppermint shrimp could be the guilty party? Also have some Waving Hand Xenia at the opposite end of the tank, which appears intact.