Call it what you want, call it what you need
There's something distracting about the silence pressing in around him, Caesar decides calmly. There's no hum of distant ventilation from his office's silence. There's no sounds of traffic from a city scape. There's faint rustles and scrapes, all just at the border of his hearing, and while they haven't produced anything harmful so far, the sheer call of the unknown repeatedly draws his gaze away from his hand-held readout.
At least the cave has its own natural lighting, such as it is. Caesar holds his scanner-camera combo up at a shadow that scurries away before he can get a good look at it. Part of him is tempted to follow it, but then self preservation and common sense reassert themselves, and Caesar safely hangs back and waits for backup to arrive so that proper protocol can be observed and life and limb safekept.
... No, sorry, that was someone else. Caesar promptly follows the first large shadow he finds, striding quickly to reach the stalagmite the creature had disappeared behind. When he reaches it, unfortunately, the whatever-it-was is gone. There is, on the other hand, a very likely looking cave starting at about waist height, leading deeper into the caverns.
Caesar considers the opening for only a beat before climbing up and through. His modified GPS hasn't given any signals of being unable to penetrate the surrounding rock so far; wandering away from the rest of his team should be--well, if not absolutely safe, then at least within acceptable margins of tolerance.