You can tell the age of a denizen by the length of their hair, but only up to a point, it stops growing once it reaches the ground. On average the hair grows approximately 1/100,000 U / cycle. Using this method it's possible to estimate the age of a denizen up to 100,000 cycles, which is roughly equivalent to 1 million years {{check math}}.

Neither 'men' nor 'women' have any hair on their bodies aside from what grows on their heads. Unlike human hair the hair of a denizen is slightly less flexible, therefore it is never deliberately styled in a way that would imply a fashionable intent, it is also unbreakable so it cannot be cut.

One thing to note here, since the toughness of the hair is derived from it being the highest density grade of polytoy, it is potentially ideal for shielding. Some might wrap their hair around their neck, or drape it strategically over vital organs. Paradoxically it is also idea for lethal strikes since it can penetrate any physical material of lesser density.

It's also worth noting that some existential techniques involve 'possessing' and controlling the hair directly and then using it as a weapon, naturally this is a skill most likely adopted by older denizens. Due to these qualities denizen hair is often incorporated into the general fighting style as well, which develops as the hair grows in length.

While unmanagable in many ways denizens have still developed numerous resourceful methods for keeping their hair out of the way, e.g. crude weaves or braids, coils, knots, etc. Although one interesting characteristic of the hair is a primitive 'muscle memory', regardless of the configuration, during the night the hair will always miraculously revert to its original state.

As for color, there is only one, all denizens share the same blend of colorless semi-translucency. It might be best described as looking like fishing line or fiber optic cable, with an almost unnoticeable milky cast that only becomes visible when several strands overlap.