Ychna were massive, bioengineered, space slug-like creatures that had mouths over eighty meters wide. Long enough to coil around an orbital city, ychna were used during the Yuuzhan Vong War by the sentient Yuuzhan Vong species to mainly assault space stations and other orbital structures. One ychna was deployed in 26 ABY over the planet Duro, where it practically ate the orbital city of Orr-Om. In the last year of the war, another was part of an attack on Caluula Station.