Id immediately

well i never found any amphipod bodies so i am sure the worms ate them. the hermit was pulled out of its shell and several worms were wrapped around it and since there was no more prey aside from one hermit who was hiding in an out of reach spot all the worms just starved and are dead.

 

Don't blame the worms or starvation. Polychaetes & most marine inverts can go for long periods of time without eating. I'm guessing that water conditions killed your inverts. Small crustacea are much more sensitive to oxygen deprivation & other poor parameters than most worms & typically die sooner when conditions get bad. The worms were probably just scavenging the necrotic tissue.

 

This is exactly what im thinking, a jar is no place for any living organism to be!
Sorry to be a joy kill.

 

I like the idea of an 'ecoshpere' but you have too many variables to consider it completely sustainable... having a single dead hermit is enough to kill everything by toxifying the water with ammonia. You haven't mentioned testing anything... I'd test and see what you find.

I think a jar with no sand would be the way to go, add some cheato or other macroalgae, and one very small organism and it MAY be sustainable. Apart from that, it's probably going to be an experiment that will end in a crash each time.

 

maybe i will just try to buy a tank.