Angel8035, my 11 year old daughter is a vegetarian, too. Poor dear is always getting questions from her peer group about why she doesn't eat meat. Hard to explain philosophy to 6th graders so I have advised her to explain that she doesn't feel well when she eats meat (which is true, just not the whole story). I have a friend that worked in an office with vegetarians and meat eaters that looked over a field. One day the mobile butcher came and one of the meat eaters felt it necessary to give them a running dialogue of the whole dispatch/slaughter routine. Jerk. Being a polite girl, my daughter would never comment on another's food choices, why do meat eaters get so offended if you choose no to eat meat? I try to explain to folks questioning my daughter that being a vegetarian is like being a Hindu and not eating beef or Jewish and not eating pork or shellfish. Think of it as a religious choice and don't try to sneak chicken broth in the soup--would you mince up bacon and feed it to your Jewish friend and not tell them? Sorry for the rant. I feel better.
Anyway, you could look in to getting aquarium substrate designed for salt water tanks. They vary from sand to crushed coral to crushed shells. Many advertise that they do not harm coral reefs and mine the substrate from ancient coral beds:
http://www.petsmart.com/product/index.jsp?productId=2753225 This is just one of many examples that you can get from your local pet store if they carry salt water fish. Prepackaged in small amounts and sometimes you can even buy it in bulk from a bin if the store is big enough so you can get just as much as you like. I hope this helps and I get your point of view even though I eat meat.