Thalassinoides

Thalassinoides is an ichnogenus of trace fossil (fossil records of lifeforms' movement, rather than of the lifeforms themselves) used to refer to "dichotomously or T-branched boxworks, mazes and shafts, unlined and unornamented".^[1]: 179 Facies of Thalassinoides increased suddenly in abundance at the beginning of the Mesozoic.^[1]: 251 Such burrows are made by a number of organisms, including the sea anemone Cerianthus, Balanoglossus and fishes, but are most closely associated with decapod crustaceans of the (former) infraorder Thalassinidea.^[2]

Thalassinoides
Thalassinoides, burrows produced by thalassinideans, from the Middle Jurassic, Makhtesh Qatan, southern Israel
Trace fossil classification
Ichnogenus:	†Thalassinoides Ehrenberg, 1944

Gallery

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  Thalassinoides burrow system in the Sherborne Building Stone (Jurassic, Bajocian) of Dorset, England; slab cut parallel to bedding.
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  Thalassinoides burrow system in the Sherborne Building Stone (Jurassic, Bajocian) of Dorset, England; slab cut perpendicular to bedding.
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  Thalassinoides burrows give a unique texture to this crest carved from Ordovician Tyndall limestone.