GoKawiilI found a seashell in the middle of the desert
To my amazement, I found a fully solid rock that eerily resembles a seashell at the base of a cliff in the Alghat desert, Saudi Arabia. I didn't know what to make of it at first, it had the swirls and shape of a seashell but was fully a rock, more importantly, it shouldn't be here; the nearest coastline is Dammam's, 500 km away.
This looks impossible
Carbonate rocks (e.g. limestone), marine fossils, coral fossils, and sedimentary structures (like ripples or bioturbation) all exist in and around Alghat, which points to the fact that parts of the Arabian Peninsula were once submerged under the sea. Specifically in the late Jurassic age (~150 million years ago)[1].
Stratigraphic distribution figure of areas near Najd[1]
Nevertheless, I was still super curious about the fossil I found; what animal inhabited it? what did it look like back in the Jurassic age? any modern relatives or lookalikes?
The proper way of answering these questions is to conduct a detailed analysis of the fossil (e.g. via inspecting the sediment it was found in, its shape, etc.), this should be done by an expert paleontologist. However, I know no paleontology, or any paleontologist, so I figured I could DIY it myself (how hard could it be..?), though I'll do it strictly via its shape — or what's called its morphology. Morphology alone is probably not accurate enough to discern lineage as different species might lookalike but are from different lineages, so this is probably not the best way to do it, but it sounded fun and intuitive, so I gave it a try.
Concretely, I plan on:
Mathematically representing the shape of a shell Defining a distance metric between shapes (so that I can find shells similar to the fossil's) Mapping out the space of shapes
7894 different species and 59244 images of shells were in the Zhang, et al. shell dataset[2]; good enough for me!
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