Field note. The human carries a cluster of small serrated metal tongues, bound together at one end by a ring, and it will not be parted from them.
I observed the specimen pat its own outer membrane four times before leaving the dwelling, each pat a check for the presence of these tongues. The metal is worn smooth at the grip end and toothed at the other, no two alike. The specimen inserts one tooth into a slot, rotates it a fraction of a turn, and a barrier that was solid becomes passable.
This is repeated at the dwelling, at the mobile pressurized box, at a smaller box where they store the temperature-controlled liquids. Each barrier answers only to its assigned tongue. The specimen has memorized which is which by touch alone, in darkness, without looking. This is the only demonstration of skill I have logged in the subject to date.
The cluster produces a distinct percussive jingle with every stride. The human does not silence it. A predator would hear it approaching from great distance. I conclude the sound is deliberate, a territorial announcement, or possibly a mating signal.
Correction. Several tongues on the ring fit no barrier the specimen owns. One is bent. One belongs to a dwelling the subject vacated many rotations ago and cannot enter. The specimen keeps these dead tongues attached, carries their weight daily, and cannot explain why when I probe. It says only that it "might need it."
I have reclassified the object. It is not a tool for opening. Most of the tongues open nothing. It is a record of every barrier the organism has ever been permitted to pass, worn against the body, jingling, so that the human is never quite alone with the doors that no longer know its name.