There is one patch of this about 1 meter diameter on a jetty rock in 20ft depth. To the eye it appears as dead plant stalks or roots. With a 60mm lense the fine white structures on the outside of the stalks becomes evident, lopophores. Tiny lopophores = encrusting bryozoans? If you look at the full resolution copy of this image you will see a lot of life in the background "twigs".