DescriptionUSNM PAL 57487 Sidneyia inexpectans.jpg English: USNM PAL 57487 Sidneyia inexpectans Collected in Canada (licensed under http://creativecommons
DescriptionDiorama of the Burgess Shale Biota (Middle Cambrian) - Sidneyia, hyoliths.jpg English: The Middle Cambrian-aged Burgess Shale is the most famous