Patella aspera Patella aspera Patella aspera is a species of limpet, a type of sea snail in the family Patellidae. Long considered to be a subspecies of "Patella ulyssiponensis", genetic evidence supports its recognition as a separate species. It is native to Macaronesia. It is known by the common name Azorean limpet, and its local name is "lapa brava". This species lives on rocks in the shallow sublittoral and intertidal zones. It is a keystone species which is of ecological importance as a grazer. It is collected for food. Overharvest is the main threat to the species, which has faced population declines
Composition of the human body Not all elements which are found in the human body in trace quantities play a role in life. Some of these elements are thought to be simple bystander contaminants without function (examples: caesium, titanium), while many others are thought to be active toxics, depending on amount (cadmium, mercury, radioactives). The possible utility and toxicity of a few elements at levels normally found in the body (aluminium) is debated. Functions have been proposed for trace amounts of cadmium and lead, although these are almost certainly toxic in amounts very much larger than normally found in the body. There is evidence that