Originally Posted by haus
I have seen him up against the glass 5 times turned inside out.
Nothing to be concerned about. This is how most species of starfish digest their foods, outside the body. The stomach is excreted around the food, dissolved and the nutrient taken in.
Some stars are actually quite large waste producers and will release large amounts of waste into the water column, more commonly with brittle stars and the like (predaceous types). This will moreso be a light colored milky liquid (kinda gelatinous) that will rise free of the body. While easting, nothing is released.