They're concretions and have been shaped accurately as described. I live to tell the tale Kodiak Island in Alaska and there's a Seaside known as Fossil Seaside that has concretions eroding out the cliffs of mud/sandstone. Little round boulders and mid-size round boulders litter the Seashore

Ideas that were the moment thought of as science fiction or The premise for your 1985 John Hughes’ Film, Odd Science, are edging closer to actuality. Desktops now have “eyes” and may scan pictures of, for example, cats as opposed to only being programmed with a list of regulations