Self-Collected in Southeastern Massachusetts! Ships from Massachusetts!
As you can see, these slab has a plethora of Calamites specimens laid-out across it where they died a very long time ago.
Calamites is a genus of extinct arborescent (tree-like) horsetails to which the modern horsetails (genus Equisetum) are closely related. Unlike their herbaceous modern cousins, these plants were medium-sized trees, growing to heights of more than 30 meters (100 feet). They were components of the understories of coal swamps of the Carboniferous Period (around 360 to 300 million years ago).
The trunks of Calamites had a distinctive segmented, bamboo-like appearance and vertical ribbing. The branches, leaves and cones were all borne in whorls. The leaves were needle-shaped, with up to 25 per whorl.
Their trunks produced secondary xylem, meaning they were made of wood. The vascular cambium of Calamites was unifacial, producing secondary xylem towards the stem center, but not secondary phloem.
The stems of modern horsetails are typically hollow or contain numerous elongated air-filled sacs. Calamites was similar in that its trunk and stems were hollow, like wooden tubes. When these trunks buckled and broke, they could fill with sediment. This is the reason pith casts of the inside of Calamitesstems are so common as fossils.