  Fermions in nature come in several types: Dirac, Majorana and Weyl are
theoretically thought to form a complete list. Even though Majorana and Weyl
fermions have for decades remained experimentally elusive, condensed matter has
recently emerged as fertile ground for their discovery as low energy
excitations of realistic materials. Here we show the existence of yet another
particle - a new type of Weyl fermion - that emerges at the boundary between
electron and hole pockets in a new type of Weyl semimetal phase of matter. This
fermion was missed by Weyl in 1929 due to its breaking of the stringent Lorentz
symmetry of high-energy physics. Lorentz invariance however is not present in
condensed matter physics, and we predict that an established material, WTe$_2$,
is an example of this novel type of topological semimetal hosting the new
particle as a low energy excitation around a type-2 Weyl node. This node,
although still a protected crossing, has an open, finite-density of states
Fermi surface, likely resulting in a plethora physical properties very
different from those of standard point-like Fermi surface Weyl points.
