yes as nandha gopal suggest they are belongs to hydrozoan and bryozoan sp. this you can conform with help of microscopic images, the polyps will be visible only under microscope. SEM images will be better to identify in species level.
We are regularly encounter these speciemens along with our samples ( marine algal materials) and our zoology friends identified these mateirals as animals. These are not seaweeds and there is no clarity in the last photograph,Thank you