[5] Grapsus tenuicrustatus can be characterized by its deep purple to black carapace and many light colored markings while it is alive.

However, as individuals shed their shell or die, the carapace the thin-shelled rock crab leaves behind turns a bright red-orangey color.

[8] The thin-shelled rock crab can be normally be found among rocky outcrops that allow for a safe place to escape to when there are signs of danger.

[9] The range of the Grapsus tenuicrustatus is listed as Indo-Pacific, found near beaches and tidepools along the shore.

[11] Across the Pacific, the people of Hawai'i ate the crabs raw and lightly salted when the seas were rough.