A crosier is the pastoral staff conferred on bishops at their consecration. From around the 7th century in the Western church it was seen to be as much the insignia of pastoral office - the symbol of the Good Shepherd - as a sign of episcopal authority.
This piece originally formed the upper terminal of an ecclesiastical staff. The tau-cross form was used in England, both before and after the Norman conquest. In the Old Testament (Ezekiel 9,4) the mark of the Tau is a symbol of righteousness, and thus it is particularly suitable for marking high ecclesiastical office. A French twelfth-century tau-cross head in the V&A shows, on its underside, two ecclesiastics, one holding a single volute pastoral staff (shaped like the St Nicholas crozier 218-1865) the other holding a tau-cross staff. Both of these forms existed together for some time, but around the beginning of the thirteenth century the single volute form becomes more usual. Two other tau-cross fragments, one in the British Museum and another found in excavations at Battle Abbey, very close to each other in design and execution, show foliage that is related to that on the present example, but are of less complex form and would seem to be of the early twelfth century.

This piece represents a tour de force of walrus ivory carving. The skilful carving and intricacy of this ivory indicates, how high the standard of English carving was in the mid-twelfth century, although sadly only a small proportion of works has survived.