they provide a bridge between different species
concrete, or the key stone (stone in middle of an arch construction)
One of the most important finds was the Rosetta Stone.
An example of a keystone species is the sea otter. Sea otters help maintain the health of kelp forests by controlling sea urchin populations, which in turn allows the kelp to flourish. Without sea otters, sea urchins can overgraze kelp forests, leading to a cascade of negative effects on the entire ecosystem.
The ISBN of The Stone Key is 9780670071340.
The Stone Key has 1000 pages.
Any one with any interest in old Egypt has to consider the Rosetta stone as important, b/c it was the key thing that made it possible to translate the hieroglyphs.
The Stone Key was created on 2008-02-04.
I know that the top stone, is called a Key stone.
the key stone is the stone that is at the top of an arch. It is this stone that absorbs the majority of the forces stabilizing the arch formed
Key-stone.
The key stone is the stone placed at the apex of the arch, and prevents the two sides of the arch falling in and collapsing.
adaptability is key to long term survival of any animal species