Common vanitas symbols include skulls, which are a reminder of the certainty of death; rotten fruit, which symbolizes decay; bubbles, which symbolize the brevity of life and suddenness of death; smoke, watches, and hourglasses, which symbolize the brevity of life; and musical instruments, which symbolize brevity and the ephemeral nature of life. Fruit, flowers and butterflies can be interpreted in the same way, and a peeled lemon, as well as accompanying seafood was, like life, attractive to look at, but bitter to taste. There is debate among art historians as to how much, and how seriously, the vanitas theme is implied in still-life paintings without explicit imagery such as a skull. As in much moralistic genre painting, the enjoyment evoked by the sensuous depiction of the subject is in a certain conflict with the moralistic message.