Once upon a time, Pebble engineers crafted a small number of watches with a completely transparent casing. They were never intended to be used for public consumption (hence the discoloration from the product's glue), but rather were conjured up as internal validation devices. After enduring heaps of strenuous testing, only one of the watches is still functional -- and our old friend Myriam Joire brought it with her to Expand. After taking a peek at the watch, it's easy to see why it would've been so ideal for internal testing purposes: you can see virtually every part of the watch, both inside and out. The gallery below won't feature any new information that the iFixit teardown hasn't already revealed, but it's fascinating to have a closer look at a different kind of Pebble that we haven't seen before.
Update: We've been told there are actually a couple other functional ones floating around the ranks of Pebble, but they're still quite rare.