Alpha Quadrant species.
The Xyrillians' most distinctive physical characteristic is their colorful dermal plating. The Xyrillian ship encountered by the Enterprise NX-01 in 2151 had a bioluminescent enviroment, and an interesting grass that grew on the ship walls. This was actually food, and released a vapor necessary for metabolization. Though the Xyrillians required technical assistance from the humans, they were quite advanced in some areas, and already had possession of holodeck technology. The Xyrillian Ah'len demonstrated this technology for Trip Tucker. Xyrillian reproduction involves placing the female's genetic material into a male host.