Pseudomorph, offers a natural phenomenon

Limonite Pseudomorph- a natural phenomenon. It is a mineral(s) that replaces the original minerals, resulting in the same shape but different composition (see Wikipedia for good definitions).
This occurs over a long geologic time, which makes it truly antique!
It is very heavy for its size, in this case roughly 2.5 inches. Thus it likely has a high iron content.
There is nothing delicate about this particular specimen. The points will not break easily, unless a strong arm with a big hammer would have a serious go at it. offers