Endlessly fascinated by earthworms for most of his life, Charles Darwin finally culminated his interests in his last book The Formation of Vegetable Mould through the Action of Worms with Observations on Their Habits. In it he describes an experiment testing the reaction of worms to sound by using a piano and other musical instruments.
“Worms do not possess any sense of hearing. [ ] “When placed on a table close to the keys of a piano, which was played as loudly as possible, they remained perfectly quiet.” He further added, “Although they are indifferent to undulations in the air audible by us, they are extremely sensitive to vibrations in any solid object. When the pots containing two worms which had remained quite indifferent to the sound of the piano, were placed on this instrument, and the note C in the bass clef was struck, both instantly retreated into their burrows.” [ 2 ]