Gabriel’s Report About Orthoceras

By Gabriel Minich

Orthoceras is an extinct relative of squids and octopi that lived during the Ordovician period. The name Orthoceras comes from Greek, meaning “straight horn,” which perfectly describes their long, pointy shells.

Orthoceras Features

• The shell is straight and is shaped like a cone. It often reaches several feet in length.
• The inside of an Orthoceras is divided into chambers by thin walls. A central tube ran through the chambers, which helped the animal float. 
• Movement: Likely used jet propulsion by expelling water, similar to modern cephalopods.
• Diet: Carnivorous, feeding on smaller marine organisms using tentacles and a beak-like jaw. 

Fossil Significance

• Common Fossils: Their strong shells fossilized well, making Orthoceras one of the most commonly found Paleozoic fossils.
• Global Distribution: Found in limestone and shale deposits across many continents. Scientific Value: Used as index fossils to help date rock layers and understand ancient marine ecosystems.   
• And just for fun—Orthoceras fossils are often polished and sold as decorative items or jewelry due to their striking appearance. 

A polished Orthoceras specimen from Morocco. Photo date 2025 by Gabriel Minich.

About the author: Gabriel is 8 years old and is in third grade. He has a deep interest in science and recently joined Pebble Pups. 

Iris Wild Wins First Place Award

Iris won first place in the National Park Service art
competition that honored National Fossil Day and another
first place award from the American Federation of
Mineralogical Societies

 

Types of Rocks

 

A prehistoric crayfish

A prehistoric crayfish, Enoploclytia porteri 

By Riley Newman

Grand Traverse Area Rock and Mineral Club Pebble Pups

 

National Fossil Day

     Each year the Pebble Pups celebrate National Fossil Day which is October 15. We also participate in the National Park Service's fossil art contest. Watch for further details on how you can participate.

Coquina

 Brody Dymond

Coquina is a type of sedimentary rock composed mostly of  shells and fossils. They can vary in hardness, ranging from crumbly to more hard like cement. The word Coquina comes from the Spanish word for “cockle” and “shellfish.” 

Coquina can be found all over the world. It forms when shells accumulate in shallow water areas where waves break such as beaches, bars, and raised banks. They are usually formed from salt water organisms, though Coquina that contain freshwater organisms can also be found. Some of the organisms that form Coquinas include mollusks, brachiopods, trilobites, and other invertebrates. The shells in Coquinas are usually 2mm or larger. 

The specimen I studied was an Ordovician period coquina limestone from the Cincinnati Arch near Liberty, Indiana. This specimen was totally packed with fossils and fossil fragments, and is very hard. Fossils included bryozoans, brachiopods, horn corals, and other organisms.

The photos below were taken by Brody with a digital microscope. 

Sources

https://legacy.igws.indiana.edu/compendium/harrodsburg-limestone

https://en.wikipedia.org/wiki/Coquina

https://www.sandatlas.org/coquina/ 

https://www.volusia.org/residents/history/volusia-stories/plantation-ruins/coquina-floridas-native-stone.stml 

Brody Dymond is a 5th grade science lover with a sketchbook full of Earth facts and creepy creatures.

Pebble Pups Celebrate National Poetry Month

 Grand Traverse Area Rock And Mineral Club's

Pebble Pups Celebrate National Poetry Month

Pebble Pup Haiku Poetry

 

Inside is lightning
It looks kind of like copper
The shape of a state
—Brody Dymond
 
Metamorphic rock
It shines like a red diamond
If is very hard
—Brody Dymond
 
Gray coral with holes
It looks like a nest of bees
But it’s really not
—Brody Dymond
 
 

 
 

Pyramid Poems

 

Ice Age Mammoth

Large, hairy

Stomping, running, living

I wish they weren’t extinct, don’t you?

—Landon Chichester

Dinosaur

Big and fierce

Stomping, eating, fighting

I would like to see a dinosaur (if it didn’t eat me)

—Brody Dymond

 
 

Ocean

Cool and clear

Alluring, waving, and sailing

Source of marine life. Would you go swimming here?

—Elly Maher

 
 
 
 
The Diamonds
Hard and beautiful
Shinning and sparkling
Quietly
Hidden with sapphires
—Elly Maher
 
Fossil
Hard and rough
Hiding and asleep
Quietly
A fossil fish
—Landon Chichester
 
 

A Diamond
Clever and blue
Wanting and waiting
Awesomely
The hardest mineral
—Brody Dymond