ctenidium
/ˌtɛnɪˈdiəm/Definitions
1. noun
A small, usually slender, hair-like or thread-like appendage, especially one of the thin, hair-like filaments that connect the tentacles to the mouth in certain invertebrates, such as cephalopods and some types of worms.
“The ctenidia of the octopus play a crucial role in its ability to move and feed.”