The lassimater was a wooden wind instrument that purportedly made the most beautiful music in the universe. According to the Tenth Doctor, it was part flute, part recorder and part didgeridoo.

The Child of Music played the lassimater once every ten years in the Concert of the Most Beautiful Music at the Church of the High Exalted on Cantabulous Nine. He did so for 320 years by the time the Doctor and Donna Noble came to hear it.

The instrument was also a prison for the small creature inside it, which only woke when the Child of Music blew gently into it. The Doctor freed it, shattering the famous lassimater.

The gift shop in the church's foyer sold small plastic lassimaters. (PROSE: Most Beautiful Music)