This little aquarium attaches to baby's crib and plays music while little fish and sea creatures swim about. There are three settings: (1) music, lights, and bubbles, (2) music and lights, and (3) music only. The music plays for 10 minutes and then shuts off.
I actually was surprisingly delighted by this crib attachment. The music is relaxing and the sea creatures are cute. My daughter likes it more as a toy than a sleep-soother, but it has helped her to enjoy her crib more. It's nice to have something to distract her for a few minutes here and there during the day too.
The only downside that I can see is that the attachment is designed for old-fashioned cribs and does not fit well on more modern styles. If you have a newer crib, you will have to attach the aquarium at the head or foot of the crib instead of on the sides. It's not ideal, but it works...and I would buy it again.