I agree with
@Horntoad; we had ruled out trawl floats with ears for the simple fact that the unidentified item will not float...it's hollow, it's made of metal with some type of coating (rubber or plastic).
Best to keep searching for the true identity of the item and not assume that something with a similar shape is the same item. The floats are a solid material that floats and are almost always a bright, highly visible color.
Let's not mark this solved just yet.
Edited to add:
Someone said that if it is metal and hollow it will float. I strongly disagree. Have you ever been sitting in a metal boat that filled with water...believe me; a hollow metal item once filled with water will most definitely not float.
