Memory is stored in so many places. A sea shell contains the memory of the organism that made it. Its trials and tribulations are recorded in the layers of material it deposited. Since it was unable to make a meaningful decision based on these memories, we hesitate to call them so, but our scientists eagerly read them, read the memories in whole stratas of seashells, the memories of entire ecosystems.
We implicitly recognize this when we say something like "this house is full of memories". Every nick and change, unnoticeable by some, tells a tale of something that happened there. The patterns of wear on the floor, the neglected dusty corners tell tales as well.
Forensics is the art of reading memories from these structural changes. Reading memory from these things we hesitate to call memory because they are not immediately accessible to a living process. But memories they are.
We have a collective memory too. The most obvious and directly accessible is books. But we have memories in our cities, in our tools, in the structures both great and small. They are like mankind's seashells.
We think of ourselves as relatively self contained. We are divided from the world by the interface of our immediate perceptions. But that division is fuzzy and indistinct. We are much larger than our bodies. And much of our memory lives outside our heads.