The definition of symbiosis has varied among scientists. Some believe symbiosis should only refer to persistent mutualisms, while others believe it should apply to any type of persistent biological interaction (i.e. mutualistic, commensalistic, or parasitic).
The Golden Pledge, which is a System Plus Warranty with a 20 year leak guarantee, can pay for itself within the first ten years, sometimes many times over. The System Plus transforms the normal warranty by removing the small print.
1 The ring can serve as a reminder of their friendship and their commitment to keep in touch. 2  Purity: A promise ring may be used as a tangible symbol of purity, either from a pledge to remain sexually abstinent until marriage or a promise to remain pure from undesirable influences, such as drinking, smoking, or drugs.