Sanctacaris is a Middle Cambrian arthropod from the Burgess Shale of British Columbia. It was most famously regarded as a primitive chelicerate, a group which includes spiders and scorpions, although subsequent phylogenetic studies have not always supported this conclusion; it is best accommodated in the arachnate clade (i.e. as a stem-group chelicerate).

 Sanctacaris specimens range from 46 to 93 mm in length. The head bears five pairs of grasping appendages and a sixth pair of large separate appendages. The grasping appendages each bear a short antenna-like second appendage. There are 11 body segments, each with a pair of walking legs and gills. There is a broad, flat paddle-like telson.

  Репродукция:

 И ещё одна:

 Ископаемые останки: