''Portalia mira'' is a fossil from the

Burgess Shale The Burgess Shale is a fossil-bearing deposit exposed in the Canadian Rockies of British Columbia, Canada. It is famous for the exceptional preservation of the soft parts of its fossils. At old (middle Cambrian), it is one of the earliest foss ...

that was originally described by Charles Walcott as a

holothurian Sea cucumbers are echinoderms from the class Holothuroidea (). They are marine animals with a leathery skin and an elongated body containing a single, branched gonad. Sea cucumbers are found on the sea floor worldwide. The number of holothurian ...

echinoderm An echinoderm () is any member of the phylum Echinodermata (). The adults are recognisable by their (usually five-point) radial symmetry, and include starfish, brittle stars, sea urchins, sand dollars, and sea cucumbers, as well as the sea ...

. A later interpretation by F. Madsen in 1957 posits ''P. mira'' as a sponge.

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* Burgess Shale animals Enigmatic prehistoric animal genera {{cambrian-animal-stub Fossil taxa described in 1918 Cambrian genus extinctions