[3][4] Cardisoma crassum is common among mangrove roots, where it builds its burrow.

Burrows dug by Cardisoma crassum are complex, often over 2 meters deep and located in high areas of mangroves with a water reservoir at the bottom of the burrow.

[5] A new species of sand fly in the genus Culicoides was found to be living and breeding in mouthless crabs' burrows, and was subbed C. cancer due to the crab connection.

[6] Cardisoma crassum is a fairly small species with a carapace broader than it is long.

[2] Mouthless crabs are colourful, with a dark blue carapace, red walking leg dactyli, and a large cheliped with a pale yellowy to dirty white top and cream-coloured underside.