That dark green or black wrapper around your maki roll is called nori, and it's just seaweed that's been dried and pressed into sheets. It's crispy, faintly ocean-flavored, and it's the reason your fingers smell like low tide for an hour after eating. You're welcome.
Sushi Ingredients
Here's a wild fact: nori sheets were originally scraped off the bottom of boats and dried. I am not making this up. Today, it's farmed and processed to be squeaky clean, so you can stop imagining barnacles in your lunch. Just don't look up the 18th-century versions unless you're feeling brave.
