Last week we purchased a very large sea apple. The store told us he/she was healthy and thriving. We would like some general info. about these creatures. It's eating all day, but changes shape often. Any information about these guys would be helpful from an experienced person. What do they look like when their happy? upset? or dead? We know their filter feeders and have the appropriate food, just always looking for more information so we can care for this guy to keep him healthy.