With the continuous development of human society and the continuous rise and expansion of cities, the contradiction between human beings and nature has become increasingly prominent. Many animals are on the verge of extinction due to the invasion of living space by human beings. Most of the old generation have such memories in their childhood: in the summer evening, the flashing fireflies in the grass are like the stars in the sky. They are in twos and threes, high and low, just like the curious childlike spirits carrying lanterns. Nowadays, Our generation lost this beautiful memory. Most of us have not even seen fireflies. Therefore, we want to place our devices in the city to recall the beautiful memories of the harmony between human and nature in the past. We choose to place the device in residential areas of a big city. During the day, these floating balls are heated and expanded, gather to cast a shadow, and provide a place for residents to stay; at night, these balls are scattered due to contraction, and release the energy stored in the day to light up, and the scattered light floats in the air, as if the fireflies are flying. The old people were able to relive the good memories of their childhood; young people come back from work at night, and their way home is illuminated by a little fluorescent light, therefore, they feel warm and comforted; for children, this is an unprecedented new experience, and will become an diatant dream when they grow up. The warm fluorescent light not only brings people light, warmth, joy and beauty, but also reminds people of decades of damage to nature and reminds people to chersh, respect and protect nature.