Something is chopping off my starfish arms!

[gobytron]

More than likely, this is your starfish starving to death....

Do some research into it, you'll see in less established tanks (and even very mature systems) many echinoderms simply starve over time.

It can last months or days.

[MMAX]

A while ago I put in a sand sifting star without properly acclimatizing him. He proceeded to drop off his arms one at a time then went to the big sand bed in the sky.

[Norstar]

Whoa. Had no idea. It's a well established tank. I'll look into it. Thanks all!