Pyrosome
（重定向自Pyrosoma）
![](/Images/godic/202502/05/Combjelly4751.jpg")
![Section through the wall of a pyrosome (magnified) showing a single layer of ascidiozooids; br) branchial orifice; at) atrial orifice; tp) process of the test; br s) branchial sac](/Images/godic/202502/05/Pyrosoma_0014752.png")
![Pyrosome found floating dead in 2010 near the Gulf of Mexico.](/Images/godic/202502/05/Pryosome_oil_spill4752.jpg")
Pyrosomes, genus Pyrosoma, are free-floating colonial tunicates that live usually in the upper layers of the open ocean in warm seas, although some may be found at greater depths. Pyrosomes are cylindrical- or conical-shaped colonies made up of hundreds to thousands of individuals, known as zooids. Colonies range in size from less than one centimeter to several metres in length.