I have the same prob. seems like many black thread like things in my green buttons and they refuse to open up. however there is no "tails" and it looks like it's dead and not moving at all. it appeared when i shifted the position of the buttons nearer to the lights. now they are mostly swept away by water currents, i suppose other inhabitants are not harmed in any way. the skunk shrimps continue to climb onto the buttons and poke at it.
do i need to do anything? my buttons wun open up.