Symbolism, Imagery, Allegory
On the Circle's main campus in San Vincenzo, most of the buildings feature glass prominently. Some even have glass floors and ceilings in addition to their glass walls. Lucite and plexiglass are other favored materials at the Circle, and even the shark, octopus, and seahorses that Tom Stenton brings back from the Mariana Trench are transparent, too.
The Circle's obsession with transparency is part and parcel of its commentary on our social media-saturated world. Since the novel is suggesting that it's neither healthy nor wise for people to willingly reveal so much of themselves online, it makes sense that Eggers would pile up examples of transparent objects and transparent behaviors to help him drive his point home.
In the end, in fact, "transparency" just turns out to be a buzz word masking a frightening reality: the more transparent you are, ironically, the easier you are for the predators to prey on.