When Charles Darwin was old, he stayed at home and observed the earth worms in his garden scientifically. He observed them at night by candlelight, he played musical instruments at them: the piano. The tuba. He noted how they reacted to the light, to the sound, to different tiny meals he offered them.
Friends and colleagues from around the world also observed their local earthworms and sent him letters with collected data.
Darwin wrote a popular science book about his process and findings. It’s here, at Project Gutenberg, for free. It’s a wonderful read.