Sure, there are shells to be found, but local shores also offer up other oddities, such as mermaids' purses, parchment worms, sea pearls, ship parts, even oysters cemented to a child's Batman belt. I've found eggs that are not broken that have goose neck barnacles attached to them, which means that they have been tossing around in the ocean a couple of months and have washed ashore unbroken. I've seen it several times. I figure it's just garbage being dumped from passing ships. You also find a lot of animal bones that may be soup bones that have washed ashore.
Some shells form a kind of cement and cement themselves to hard objects.
I have spiny oysters attached to a Batman belt, a D-cell battery, a piece of a gun, and plastic and glass bottles, just to name a few. Lloyd used to help people identify their unusual finds when she taught at the Marine Science Center. She's seen Indian artifacts and fossils and, of course, sea pork. Sea pork looks as gross as it sounds, but many people excitedly brought it to the Center thinking it was ambergris, which is almost as bad. Ambergris is basically whale vomit.