This specimen likely began as a mound of limonite matrix, upon which the calcite was deposited before some natural (or anthropogenic) process removed the matrix, leaving a concave calcite shell behind. The calcites are translucent and reach 1.7 cm. Many of the smaller calcites have red brown hematite inclusions. Minor edgewear on one of the larger calcites is not an issue at this price. Displays nicely.