closed as unclear what you're asking by gerrit♦ Nov 2 '18 at 12:02
Please clarify your specific problem or add additional details to highlight exactly what you need. As it's currently written, it’s hard to tell exactly what you're asking. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.
I am pretty sure this is a concretion. Concretions come in many forms... see the wiki page on concretionsWiki Page on Concretions. Your particular example appears quite uniform. Sometimes you can find fossils in the interior but I would be reluctant to cut or break open your concretion.