Meerschaum

Meerschaum, also known as sepiolite, was a hardstone found in the Realms used for carving.

Description
Meerschaum was a white, compact, porous, clay-like stone used for pipes and small carvings. It was light and easily quarried and transported in large quantities. A typical price for this raw material was 2 gp per pound (0.45kg).

Powers
Using a unique spell called stretchbone, meerschaum could be transformed to look like real bone, suitable for replacing missing bones in a skeleton. The animate dead spell required skeletons to be mostly intact to be effective, and as long as there was at least one real bone in the skeleton, the rest could be made of meerschaum and it would still animate.

Rumors and Legends
Meerschaum was the subject of various repulsive rumors due to its association with necromancy, but none were ever proven to be true. It was also said that certain wizards new how to prepare a sample of this material so they could later cast wizard eye and clairaudience through it from a distance.