He walked into the kitchen with his boots on, making/leaving muddy 'footprints' on the floor.
The new model has a smaller 'footprint' than the older model.
The child left her tiny 'footprints' in the snow.
(..) Trying to answer this in any meaningful way outside of being able to see them and hear them, the heptopods leave absolutely no footprint. The chemical composition of their spaceship is unknown. The shell emits no waste, no gas, no radiation. Assuming that the shells (..)2016 Arrival