Those used by bishops have curved or hooked tops, similar in appearance to staves traditionally used by shepherdss, and representing the bishop's office as "shepherd of the flock of God." Crosiers carried by abbots are similar, but usually smaller, and carried with the curve toward the back rather than toward the front as with bishops. Those carried by archbishops more typically have a cross at the top.
A crosier was also carried on some occasions by the pope beginning in the early days of the church. This practice was gradually phased out and had disappeared by the time of Innocent III's papacy in the eleventh century. It was later revived; John Paul II is often seen using a crosier after the archbishop's style.
The term derives from the Old English word crycc, meaning "crutch."
The crosier is conferred upon ordination into office.
References
The coiled ends of some plants (such as unopened fern fronds) which resemble the above-mentioned traditional staff are also termed "crosiers" (though these are more commonly called "fiddleheads").