Dan,
Not to gild the lily, but you might check out Kristina Turner's "The Self-Healing Cookbook" (
http://www.macrobiotics.org/kistorebooks.html, http://gomf.macrobiotic.net/Books_Cook.htm, ).
She talks about (and shows you how to cook) hijiki, wakame, kombu, bok choy, Chinese cabbage, mustard greens, radish greens, turnip greens, and watercress, among other excellent sources of calium and other minerals.
She says "Did you know that the body's calcium reserves get depleted bydrinking soda pop, eating too much protein, and not getting enough exercise. Eat sea veggies to help restore those losses."
Thank you, very much.
Bruce Paine