The basic habit of a Coptic monk is made up of a leather belt worn under a long, black gown, a black skull cap and a black hood. When a monk is also a priest and is taking a liturgical service he changes into similar garments, but in white.
The hood worn by Coptic monks is called a koulla (Coptic), but it is now commonly referred to as qalansuwa (Arabic).
There are various ideas and traditions within the Coptic Church about where the idea for the hood comes from. One thought places the origins of the hood back to the garments of late antiquity in Egypt. In the early centuries of the first millennium AD it was not uncommon for children’s tunics to have a hood. The tradition says that the monks took the idea of the hood as a symbol of (childish) innocence. Some tunics at this time also had deep splits at the sides, which are said to have developed into the monastic scapular (a length of cloth suspended both front and back from the shoulders of the wearer), which is worn by monks and priests in both Eastern and Western Christian Churches. In the Eastern Churches, the hood was detached from the scapular.
Another story relates how St Anthony gave Coptic monks their distinctive black hoods. According to this tradition an angel asked St Anthony to wear the hood, shaped like a baby’s bonnet, to remind him to be simple and pure like a child. The devil, however, tried to pull the head covering off. St Anthony caught it, ripping it down the middle. Today the head covering is stitched down the centre where the material was torn in two, symbolizing the conflict between good and bad, the devil and God, which still continues in the world. Another symbolic meaning that has been given to the hood, is based on the texts read during the ritual when a novice becomes a professional monk. The Hood is said to represent the Helmet of Salvation from the Spiritual Armour of St. Paul:
Stand therefore, having girded your waist with truth, having put on the breastplate of righteousness, and having shod your feet with the equipment of the gospel of peace; above all, taking the shield of faith with which you will be able to quench all the flaming darts of the evil one. And take the helmet of salvation, and the sword of the Spirit, which is the word of God (Ephesians 6:14-18).
These hoods are decorated with twelve small crosses placed in two groups of six, and one single cross. The grouped crosses represent the twelve disciples and reminding monks to follow their teachings. On the back of the hood is a single cross that symbolises Christ. Again it is said to be symbolically placed to remind the monks that they must leave everything earthly behind and only look to God.
A monk receives his hood during the rites involved with his first degree of profession (mikroskema) and he should never take it off. The present model of hood was re-introduced in 1971 by Pope Shenouda III, after it had fallen into disuse for some two to three centuries. It was based on the model worn by Syrian Orthodox monks. There is no reliable information about the exact model before the 18th century.
Coptic nuns also wear a similar hood. These hoods are not normally seen as they are hidden by the nun’s veil. The history of the nun’s version is not known, but it is likely that it was only introduced for nuns in 1971.
From http://stnoufer.wordpress.com/2010/11/10/the-koulla/