Polymorph the Spitelash of Azshara and kill the clones that appear several seconds later. When you have slain 50 Polymorph Clones, return to Archmage Xylem in Azshara.
My research has revealed a unique purpose for the prismatic shell.
Carry the shell and cast your polymorph spell on the Spitelash in Azshara. If you wait a few moments, the chaotic aura of the shell will cause them to split into several smaller clones for a few moments. Kill these clones as quickly as possible, and the shell will collect their essence.
