Dead Stuff

[Rikko]

I had a few hitchhiker (well, they grew out of the rock quickly) sea squirts that stuck around in my tank for a few weeks.. When they died they just sort of vanished.
For anemones, sometimes they can look like hell and still be ok (just sulking). I find the best indicator is if you disturb the water around them a little bit and see if pieces start coming off it. A dead anemone is a falling apart anemone. Might wanna have a siphon handy..
Another pretty surefire way is just to try moving it.. If the foot is still attached firmly to its substrate, it's still kicking.