Sandmason Crab Species in Etharai | World Anvil

Sandmason Crab

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This article was created for my Species-A-Day project for 2024! Read more here!
The sandmason crab is a small crustacean that lives in the whirlpool reefs, known for their colourful shells made from pieces of coral that have fallen away from their larger organisms. The species lives in shallow, warm water, and create their own shells. The appearance of a sandmason crab's shell varies greatly between each individual member of the species, and are hand-crafted over the span of their lifetimes from debris found on the ocean floor. When faced with a lack of material, the species is able to injest sand and compress it into a firm but moldable material, which they can use to repair cracks in their shell and even form new extensions onto it. As a sandmason crab grows, it carves out space in the interior of its shell, and adds onto the outside. On average, a sandmason crab's shell will be composed of entirely new material in the span of three years. When rearing young, adult sandmason crabs will create the initial shells for their children.


Standing at only half a foot tall at their largest, sandmason crabs would go almost entirely unnoticed if not for their colourful patchwork shells. They have sandy beige skin, and their abdomens are curled inside of their shells. They are able to retraact fully into their shells, and will do so for protection from predators or stronger currents. They have ten legs, the front three of which are used to move around. Their last two pairs of legs are used to secure the crab to its shell. The sandmason crab's digestive system protrudes from its body, curling around its abdomen. Though still protected by its shell, this leaves the species vulnurable if they are ever separated from this shelter. As such, they develop incredibly strong hind legs to ensure that the shell will never come off.
Scientific Name
Coenobita centonibus
50-55 years
Average Height
4-7 inches
Geographic Distribution

Cover image: Brown Sand by May Barros


Author's Notes

This article was created for Strixxline's unofficial challenge, Crafting Creatures!

Crafting Creatures 2024
Generic article | Apr 5, 2024

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Apr 2, 2024 13:04 by Dr Emily Vair-Turnbull

Ohh I love them. I love the image of the adult sandmason crafting shells for its babies.

Emy x   Etrea | Vazdimet
Apr 2, 2024 14:48 by spleen

little baby crabs with little baby shells :>

Have a wonderful day!