  It is shown that the generators of Clifford algebras behave as creation and
annihilation operators for fermions and bosons. They can create extended
objects, such as strings and branes, and can induce curved metric of our
spacetime. At a fixed point, we consider the Clifford algebra $Cl(8)$ of the
8-dimensional phase space, and show that one quarter of the basis elements of
$Cl(8)$ can represent all known particles of the first generation of the
Standard model, whereas the other three quarters are invisible to us and can
thus correspond to dark matter.
