Animal?, Vegetable?, or Mineral?

In the last few weeks I have found quite a few of these objects on the beach at Lundin Links, but I am not sure what they are. They are about the size of an average courgette, and they look a bit like the breadcrumb sponge, as they appear to be covered in oscula, except that they are cylindrical. I thought about a sea cucumber or sea gherkin but not at all sure. I even wondered if it was man-made tubing, that a sponge had grown round. I can find nothing that really looks like these photos either in my sea-shore field guide or in online images. However, searching on the internet, some sites mentioned that breadcrumb sponge will grow round kelp stems so I think that is my best guess so far.