Balloon Houses in the deep https://www.oceanblogs.org/msm130/2024/08/03/balloon-houses-in-the-deep/

As mucus net feeders, they build huge and really beautiful ‘houses’ around their bodies that comprise two layers of filters. By beating their tails, they drive a feeding current through those mucus houses, and in this way #larvaceans are able to concentrate food particles and other suspended matter in the water column. They discard their houses, when they get clogged and build the new filtration system.