Here is the low down on feathers:
They don't really see, they feel for any vibration or extreme current and retract as a mechanism of safety, also when their feathers feel full, they pull them in and feed off of the particles caught. At times they pop their cap and stay in the tube for a week or so and rebuild their feathers. When this happens the top of the tube collapses adn it takes a few tries for it to pop open when they are ready to emerge. Now to tell if they are dead , put it into your hand and you should feel the worm wiggle (kinda weird), no movement means it may have died. For the feather to not open, make sure they are in a indirect current and the feathers gently sway.