[Koresample]

One of my Xenias went from looking healthy to dropping its sweepers to dying within a 24 hr period and now i need to remove it from the tank. Am i best to just suction what i can of it out with a water change? I noticed one of the sweepers fell on my toad stool during the night and turned it brown where it landed, is it toxic for the other corals? All of my other corals look healthy so am not sure why this happened. It recently split into three and the other two (located lower in the tank) look healthy.