Sushi is another one of those foods I could eat anytime, everyday. And uni is one of those items on my list I actually crave for.
Uni is the edible part, or eggs (roe), of a sea urchin. It has a soft, creamy texture and my description of taste would be similar to the stomache/insides of a crab. It's sweet but at the same time, has a sea water/salt flavor to it too. This is what good quality uni should taste like. If it has a musky or metallic taste to it, it's probably not fresh or not of good quality. As I've been told, the best quality of uni comes from Santa Barbara or Japan. The color ranges from dark yellow to orange-ish. I believe the more orangy it is, the better.
Uni is usually eaten as a nigiri style, sashimi, or my preference, in a handroll with ikura. Some places even get creative and serve it in a shot glass with sake & quail egg, or on a spoon with tobiko, ponzu sauce, & quail egg, or even on oysters! On menus, the price will vary and even sometimes be quoted as "market price." It can range from $5-15+ for 2 peices of nigiri.