Camera
Traditionally, cameras have been used to preserve memories, which the dream might be alluding to, or to document events as proof that something truly happened (likely for oneself in dreams).
The camera and photography are associated with "seeing," meaning making something evident or becoming aware of something.
Nowadays, our mobile phones are used not only to preserve memories but also to shield ourselves. Instead of experiencing a special moment directly, we insert the camera between ourselves and the event to experience it later instead, which inevitably results in two incomplete experiences rather than one whole one. This screen can also serve as protection from something frightening; it is well-documented that people filming something dangerous tend to underestimate the risk, as if the act of filming itself provides a shield from reality.