From what I can remember, putting the lilies in damp soil is a way to put them into dormancy like imitating the dry season. It should be covered in water to promote growth.
I've thought about this and a number of things make lilies very appealing. First and foremost is the Aerial Advantage they have over ordinary submerged plants. It takes the whole problem of whether and how to supply CO2 to one's plants off the table. They get it directly from the air.Another birth in progress! Your porcelain bowl will soon be filled with these lilies.