 So that's a brief run through the allotropes of carbon, but carbon's not the only element to be able to bond in different ways. The Wikipedia page on allotropes has an impressive list of different element forms. Some may be familiar to you, while others only exist under particular pressure or temperature conditions. For instance, oxygen forms the familiar O2 molecule, but it also forms ozone, O3. Sulfur is in the same group as oxygen, and it's able to form diatomic molecules like oxygen, S2, but its preferred form is actually in rings of eight sulfur atoms. Phosphorus takes a number of forms. The incredibly flammable white phosphorus is made of P4 molecules, where the atoms are bound in a tetrahedron. Compare this with the tetrahedron of methane, which has the central carbon atom, which then has the bonds radiating out to the four hydrogens, which form the vertices of the tetrahedron. In this one, the phosphorus atoms are at the vertices, and the bonds actually form the sides of the tetrahedron. This allotrope has a terrible history in its use in incendiary bombs in a number of wars because it's so reactive. In contrast, the relatively stable red phosphorus allotrope has largely amorphous bonding. Tin also has interesting allotropes. See what you can find out about Tin Pest, and the trouble that it caused Napoleon's army when they tried to invade Russia.