Silica may not be a word you commonly hear associated with diet (or foods that prevent hair loss, for that matter). If youâre looking to promote hair growth and prevent hair loss, however, silica will need to be on your menu.
keystone-the central building block at the top of an arch or vault. headstone, key. arch - (architecture) a masonry construction (usually curved) for spanning an opening and supporting the weight above it. building block-a block of material used in construction work.
Giant otters are keystone species for South America river systems. A keystone species is one that plays a critical role in the way their ecosystem functions. Without that species, the ecosystem would be dramatically different or cease to exist at all.