Dunno about health benefits but I really like the seaweed they sell in Japaneses restaurants and I remember enjoying laver bread when I was younger. Recently I read about liver and or bacon being served on laver bread and I thought that sounded like the nuts. I have no idea where I would go about getting it here though.
Recently I read about some big chef experimenting with, maybe not exactly seaweed, but some kind of plant that you can grow under the water, even salt water, so you could grow it in the sea. I think he was trying to make different versions grow with different tastes straight off and also different ways to prepare it once harvested. There would obviously be huge benefits if you could grow massive amounts on the bottom of the sea and feed the world... though knowing the way these thing work it would probably get out of hand and spread uncontrollaby, starving fish of oxygen and causing some previously unknown sea monster, deprived of its usual diet of whales, sharks and giant squid, to rise from the depths and eat Tokyo or NY or something.