Background image: Medusa of Aeginura Grimaldi (bottom view) by Ernst Haeckel. Public Domain image from https://en.wikipedia.org/wiki/Ernst_Haeckel#/media/File:Aeginura_grimaldii_by_Haeckel.png

References:

Metchnikoff, O., 2019. Life of Elie Metchnikoff, 1845-1916. Good Press.