The Sarissa (or Sarisa) was a 13-21 foot long pike used in the Macedonian phalanx (a body of troops standing or moving in close formation.) It was very heavy for a spear, weighing over 12 pounds. It had a short iron head shaped like a leaf and a bronze shoe that would allow it to be anchored to the ground to stop charges by enemy soldiers. The bronze shoe also served to balance out the spear, making it easier for soldiers to wield. Its great length was an asset against hoplites and other soldiers bearing smaller weapons, because they had to get past the Sarissa to engage the soldiers. However outside the tight formation of the Phalanx the Sarissa would have been almost useless as a weapon and a hindrance on the march. To this end the Sarissa was constructed of two halves and joined by the means of a metal collar before battle. This allowed the Sarissa to be broken down into much more manageable sections to increase its mobility and that of the army.
From: http://en.wikipedia.org/wiki/Sarissa
From: http://en.wikipedia.org/wiki/Sarissa