Scientists are redefining memory as a physical and biological phenomenon extending beyond the brain. Single-celled organisms like ciliates demonstrate learning and decision-making based on past experiences, suggesting memory may be rooted in molecular mechanisms common across life forms. Experiments with human and animal cells show they exhibit the 'spacing effect'—a key marker of memory—when exposed to timed stimuli, even without neurons. These findings imply that the capacity to remember might be an ancient, widespread trait encoded in cellular biology. Yet, defining what 'memory' means outside the nervous system remains contentious, requiring collaboration across disciplines to distinguish true memory from mere biological response. The implications challenge long-held assumptions about cognition and open new frontiers in understanding how life retains information.