Irene is a chemist who can be found in the northern area of the Mushroom Forest. She studies a nearby mycelium pool and explains that adding Fossils, Phosphate or Calcium may help understand its properties.
Irene mentions her mother, Marie, when spoken to. This, as well as her examine text, are references to the Polish-French chemist Marie Curie and her eldest daughter, Irène Joliot-Curie.