Dice are solids with marked sides, used for producing a random result by rolling. Most often, dice have numbered sides (with equal areas) and are rolled to produce random numbers. Typically, these numbers are used within games. The conventional die of traditional games is a cube, marked with faces marked by pips from one to six, so that opposite faces sum to seven.
Polyhedral dice have become very popular in gaming over the last few decades. References to these are often abbreviated as "NdX" where X is the number of faces on the die, and N is the number of dice to be rolled. Common dice include the d4, d8, d10, d12, d20, and the ubiquitous d6. More rare and obscure are the d3, d5, d7, d16, d24, d30, and d100 dice.
The tetrahedral d4 is a triangular pyramid, and is used in Trice.
Looney Labs Dice
Unique to the world of pyramid games is the Treehouse die, the cubical TIP-SWAP-DIG-HOP-AIM-WILD die that comes with a Treehouse set. It is now used in a variety of pyramid games. Black ICE uses multiple Treehouse dice.
IceDice are the two six-sided dice included in the eponymous IceDice: a Pyramid die (showing various sizes of pyramids) and a Color die (showing Rainbow colors and a wild burst). Later games have been designed to use these also. Later versions of the Color die used typical card suit symbols and a star instead of just circles of color, as in the original dice. It also replaced blue and black with cyan and purple.
Pyramids as Dice
Looney pyramids can also be used as dice. Each pyramid can function as a d2, a two-sided die. The pyramid has two states, upright or flat. If tossed onto a hard surface, the pyramid will likely come to rest flat on any of its four faces, but may land upright instead. However, unlike the usual d2 of choice, the coin, the two outcomes of a pyramid as d2 are obviously not balanced. Individually this feature is not impressive or useful. But if a group of pyramids is tossed, the results can be tallied, counting the pieces that land flat or upright, thus generating a random number. By varying the population of tossed pieces and the result to be tallied, various random effects could be simulated. This method could be used, for example, to simulate the effects of attrition, taxation, or migration.
Additionally, one could mark a pyramid's four faces with unique symbols or numbers, turning the piece into a reasonably fair d4 (barring weight influence due to manufacturing defects) with the added behavior of an unlikely fifth result... upright. This d4/d5 might be useful for determining critical hits or other exceptional events in an otherwise simple die-roll.