Ring me up every time you enter my house for without me you surely will be stuck about

I beat within but can be given, I break though still I keep you living. I’m more than flesh, yet still I’m true, the core of life that beats in you.

I have cities, but no houses I have mountains, but no trees I have water, but no fish I have roads, but no cars What am I

first four are found in grains, all across the world, though not ones you eat, but those that wash ashore. last three are a container, six sides to be exact. I am what UPS specializes in, when a flat envelope will not do.

I’m found in your ear and I’m found in a kit, I respond with a boom whenever I'm hit.