Punctuation is the name for marks used in writing. They are to help understanding and correct reading. These are some common punctuation marks used in English: . is a period or full stop.
In the past, less affluent Okinawans ate sweet potatoes. Lots and lots of sweet potatoes. Rice, especially white rice, was more expensive and was a bit of a status symbol: it was something consumed only by the wealthier folks.
Sea vegetables are some of the most nutrient-dense foods on the planet but, at least here in the West, are a largely neglected group of superfoods for the brain. The people of Okinawa, Japan may owe their extreme health and longevity, at least in part, to their regular consumption of sea vegetables.