The shell brought home loses the sea but keeps the reason you stopped.

Souvenirs are not really about the object. Out of the water it dulls, on a shelf it is a small dry thing with no context, and yet it holds an accurate record of a moment when you bent down because something caught you. That is what you took home. The value was never in its quality, which is why replacing it with a better one from a shop would not work at all.

Look at the odd items you have kept and ask what each one is standing in for. Anything that has lost its reason can go; anything that still holds one has earned its space.