Vertebrate fossils
Belemnite guards
The bullet-shaped 'pencils' you find in Cretaceous creek gravel are belemnite rostra — the internal hard part of an extinct squid relative. They were the dominant shelled cephalopods of Mesozoic seas before ammonites took over. Easy first find for kids.
How to spot it
- ▸Cigar- or bullet-shaped, usually 1–3 inches long
- ▸Dense, glassy calcite — heavier than it looks
- ▸Honey-amber, dark brown, or jet black depending on weathering
- ▸Often broken at one end with a hollow conical socket (the alveolus)
- ▸Look for a faint central canal running the length
Easy to confuse with
- ·Modern wood pencils (no kidding — kids find them in creek bars)
- ·Iron concretions (heavier, magnetic, no calcite shimmer)
Geological context
When you see belemnites you are in Cretaceous-aged sediment — think Navesink and Mount Laurel formations in NJ.
Reported at these sites
About the category
Bones, vertebrae, and ear-bones from extinct and modern marine vertebrates. Heavier and denser than rock of the same size, with a tell-tale honeycomb internal structure when broken.