Discovered in 2011 by French amateur astronomer Nicolas Outters, Ou4, nicknamed the Giant Squid Nebula, is a remarkably faint bipolar outflow structure located in the constellation Cepheus. Stretching across more than two degrees of sky, its ghostly blue form resembles a deep-sea squid drifting through space. The nebula is likely powered by the triple-star system HR 8119, located near the apparent center of the outflow.

Ou4 lies within the larger and brighter emission nebula Sh2-129, also known as the Flying Bat Nebula. The deep red background is dominated by ionized hydrogen (Hα) emission, contrasting starkly with the OIII-rich, oxygen-emitting outflow that defines Ou4’s structure. The nature of the Giant Squid remains under study, with hypotheses ranging from a planetary nebula to a massive stellar wind structure formed by high-energy interactions in the central system.