Selkirkia is a genus of predatory,[3] tubicolous priapulid worms known from the Middle Cambrian Burgess Shale, Ogygopsis Shale, Puncoviscana Formation[4] and the Early Ordovician Fezouata Formation.

[6] In the Burgess Shale, 20% of the tapering, organic-walled tubes are preserved with the worm inside them, whereas the other 80% are empty (or sometimes occupied by one or more small agnostid trilobites).

[3] Selkirkia had a body divisible into a proboscis towards the anterior of a trunk enclosed by a tube.

The proboscis would have been partially invertable and was armed with several spinules and spines, decreasing size distally overall.

Immediately behind the proboscis was the trunk, smooth for the most part but lined with papillae towards the anterior.