In 2016, CNRS scientists demonstrated that the slime mold Physarum polycephalum, a single-cell organism without a nervous system, could learn to no longer fear a harmless but aversive substance and could transmit this knowledge to a fellow slime mold. In a new study, a team from CNRS and the Université Toulouse III – Paul Sabatier has shown what might support this memory, and in fact, it could be the aversive substance itself.