The black box of a crashed airplane records vital information and will emit signals when contacting with seawater. What if the human civilization is “crashing”? In fact, it is! The ever-rising sea levels are going to destroy most of the current coastal cities along with their thriving economy and cultures. When cities sink into water and when humans leave, how can we prove and memorize our previous existence? Our team conceived a box to put on each building’s roof. When immersed, the boxes will glow as the hibernated fluorescent organisms inside wake up and start propagating. Also, the lens and the one-way mirror film around will collaboratively direct the lights upwards to form vertical beams. Probably, our human survivors may have to retrospect the submerged civilization by remotely watching the shimmers of those boxes from outer space.