Pneumatocyst
In phycology, a pneumatocyst is a floating structure that contains gas found on brown seaweed. A seaweed's thallus may have more than one.
en-US/ˈnumətəˌsɪst/
In phycology, a pneumatocyst is a floating structure that contains gas found on brown seaweed. A seaweed's thallus may have more than one.