# @stem_antics on Instagram

- **Type:** Video
- **Original URL:** https://www.instagram.com/p/DU0rGw5kfij
- **Gondola URL:** https://gondola.cc/posts/61935931-stem-antics-instagram
- **Thumbnail:** https://img.gondola.cc/tr:w-,h-,fo-auto/postThumbnails/b7a64b4215.jpg
- **Posted:** 2026-02-16T15:00:34.000+00:00
- **Account Owner:** Stem Antics (@stem_antics) — https://gondola.cc/stem_antics

## Caption

Ammonites were extinct marine cephalopods (relatives of modern squid and nautilus) that thrived during the Mesozoic Era. Their shells grew in logarithmic spirals, partitioned into chambers by septa (walls). The living animal occupied only the outermost chamber; inner chambers were gas- and fluid-filled, regulating buoyancy through a tube called the siphuncle.

🔬 How this fossil formed (step-by-step):
	1.	Life & growth – The ammonite secreted calcium carbonate (CaCO₃) to build new chambers as it grew.
	2.	Death & burial – After death, the soft body decayed. Rapid burial by sediment (mud, silt) limited scavenging and oxygen exposure.
	3.	Compaction & mineralization – Over millions of years, sediments lithified into rock. Groundwater carried dissolved minerals that:
	•	Permineralized the shell (filling pores with minerals), or
	•	Replaced the original aragonite shell with more stable calcite or silica.
	4.	Mold & cast formation – If the shell dissolved, it left a mold in the surrounding rock; later minerals could fill that void, forming a cast that preserves the shell’s external shape.

🧭 Why ammonites matter in STEM:
	•	Index fossils: Rapid evolution + wide distribution = precise tools for dating Jurassic strata.
	•	Paleoclimate clues: Shell chemistry (e.g., oxygen isotopes) records ancient seawater temperatures.
	•	Evolutionary patterns: Suture complexity (the intricate line where septa meet the shell wall) increased over time — a case study in morphological innovation and constraint.

This fossil is a time capsule of biomechanics, chemistry, and Earth history — all in one spiral.

What would you test first: buoyancy physics, isotope chemistry, or evolutionary design? Drop your pick below 👇
Share with someone who loves deep time.
#STEMeducation #Paleontology #Ammonite #Jurassic #Fossils EarthScience Geology STEMAntics

## Stats

- **Views:** 17,415
- **Likes:** 427
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- **Comments:** 5

## Tags

fossils, ammonite, jurassic, stemeducation, paleontology

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