This post comes from a good friend who lives in Hiroshima, but travels frequently and in this entry covers the interesting moss ball found in lake Akan. Thanks to my great friend, Yumi. Enjoy!
This summer we tripped to Hokkaido, the Northern most island of Japan.  One of the places I would have always liked to visit in Hokkaido was Lake Akan. When we were there, a sign was posted saying, "A brown bear was found a few days ago here. Would you like some bells to carry for your safety?"  They live only in Hokkaido in Japan. There are several lakes in Hokkaido, but this one in particular is famous for its peculiar moss ball called “Mari-mo (mari =ball, mo=algae)”. 

Moss ball can be found in north Europe, Russia, and North America. However, the marimo in Akan can grow up to 30cm (12 inches) in diameter, and make a lovely round shape by being rippled by lake water. 
Inside, it branches out tightly and radially and is covered with hard yet velvety green algae.  We bought our son two marimos in a glass jar.  They are not natural, but cultured.  The man at the store collects some algae, keeps it in a container, and rolls it up until nice and round behind his counter when he has some spare time for his customer.  He told us to change the water once a week and roll them between palms from time to time to keep shaped, and they would grow bigger every year.  Once I had some marimos myself.  One day I found they were broken into some pieces and thought I lost them.  According to this man the marimo cannot stay tight in still water but if we roll them they will once again make a round shape.  I wish I knew it years ago. 

The question as to whether or not water bottles can be used once and then reused seems to provoke a great deal of misinformation and very biased slants on many websites. The fear mongers talk about deadly pathogens, bacteria waiting to kill you, and in general want to scare the public. In the process, millions of bottles are added to landfills to spend perhaps 100 years or more to decompose. Well, I am here to tell you that it is simply not true. I have reused the same 4 bottles for the past 6 years and have had no problems. But, it does take a little reasonable care.
Water bottles used for drinking and carbonated beverages are blow molded from polyethylene terephthalate, (PET). It is a polymer with a long history and has been the subject of many investigations regarding safety for contact with food products. The US Food and Drug Agency, FDA, is responsible for testing protocols and acceptance of containers used for food storage and use. I am frequently critical of the FDA but in this case I have read the research and it is well documented as safe. They asked two basic questions: Does the food in the container cause any breakdown of the PET? Does the PET leach any chemicals into the contained food? The answer to both questions is no!
The International Life Sciences Institute, ILSI, a non-profit organization dedicated to advancing the scientific understanding issues of nutrition, food safety, toxicology, risk assessment, and the environment published a report in July of 2000. Italics are my comments:
“PET itself is biologically inert if ingested, is dermally safe during handling and is not a hazard if inhaled. No evidence of toxicity has been detected in feeding studies using animals. Negative results from Ames tests (test for cancer causation) and studies into unscheduled DNA synthesis indicate that PET is not genotoxic. Similar studies conducted with monomers and typical PET intermediates also indicate that these materials are essentially nontoxic and pose no threats to human health.  .  .  .  It is important to stress that the chemistry of compounds that are used to manufacture PET shows no evidence of oestrogenic (effect on the female reproductive process) activity. There is a significant body of evidence that demonstrates that the use of PET is not a concern and is perfectly safe in this respect.”
The second reason for not refilling and reusing water bottle is that “dangerous” bacteria can form and cause illness or death. Really? Of course bacteria can form under the right conditions. It can happen in any food product, in a glass of water, or a coffee mug under the right conditions. It happens every day, but water from municipal supplies generally has chlorine so the opportunity is diminished. Additionally, not all bacteria is bad! But if the water is kept safely out of the sun and heat the chance of bacteria forming is not a problem. I rotate my bottles every day and wash the used one with warm soapy water. With a little care there is no concern about reusing drinking water bottles. There is a link to FAQ's from plastics info.org here. I am still puzzled as to why people still buy billions of dollars in bottled water. There is no good reason short of emergency to spend money on what comes out of the tap...