my bf had a anemone in his tank and now i noticed its missing.He just thinks it went into hiding because we had an arrow crab in there with it and it wouldn't leave the anemone alone. A few days later its gone. now he got rid of the arrow after some complaining from me but its still not out,should i be worried? if its crawled into a rock and died could it harm the fish like raise the ammonia level? he don't have verys many fish in there juat a snowflake eel two damsels and a lawn mower blenney. im worried if its dead it could wind up killing thease animals.