Coins of the pound sterling also became known as a "pound". (240 actual pennies, however, weighed only 5400 troy grains, known as tower pound, a unit used only by mints. The tower pound was abolished in the 16th century.) The silver penny remained the primary unit of coinage for about 500 years. The purity of 92.5% silver (i.e., sterling silver) was instituted by Henry II in 1158 with the "Tealby Penny" — a hammered coin. Over the years, the penny was gradually debased until by the 16th century it contained about a third the silver content of a proper troy 24 grain pennyweight. By 1915,
Australian Grains Genebank can be distinguished: this is most important for alpine seeds, as recent proofs show that grains from cooler and wetter habitats are shorter lived than seeds from warmer ones. Longevity checks can also indicate how seeds should be conserved. The main goal of the Australian Seed Bank Partnership is to save about 1700 native species of plant and ecological communities facing extinction due to habitat loss, and the fragmentation and degradation of invasive species. To accomplish this objective, the partnership maintains a safe and sustainable environment, and collects and stores seeds to help research on the subject. The Australian Grains