cleaner shrimp dead!

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this mopring i woke up to see that one of my blue legged hermits was in half! i didnt think much of just though he got eatin while changing shells. i removed the other half. then when i got home from school one of my cleaner shrimps that i bought 2 days ago was dead. i took him out when i look at one of his sides. itlooked like somthing had crawled up inside him and there are brown spots in the hole. should i be scared? i also added about 8 pounds of live rock 2 days ago to.
my ingabbitants are: madarin, blue tailed damsel, maroon clown 10 snails, 12 hermits, star polyp, coni anemone, feather duster, brittle star, cbs shrimp, and i guess only 1 of my 2 new cleaner shrimp
thanks in advance

 

[joe's reefer]

it might be some parasite in the rock.if the shrimp seemed crushed it was a mantis shrimp.or if there were bristles on/in it it was a bristleworm.i have never seen a parasite actually bore a hole in a shrimp before.sounds like a nasty death