Callavia

Callavia is an extinct, monotypic genus of trilobite arthropods. C. broegeri lived during the late Atdabanian stage, which lasted from 530 to 524 million years ago during the early part of the Cambrian Period in what are today Canada and the United States.
Taxonomy.
The position of "Callavia" in relation to other Olenellina has shifted repeatedly over time. Initially it was assigned to the Holmiinae by Pierre Hupé, and was later moved back and forth to the Callaviinae. Lieberman, however, argues "Callavia" is a basal member of the Judomioidea.
Distribution.
"C. broegeri" is known from the Lower Cambrian of Newfoundland (Brigus Formation, Branchian Series, Conception Bay), Nova Scotia (between Docters Brook and Malignant Brook, northernmost Antigonish Highlands), Canada, and Massachusetts, USA (Weymouth Formation, Pearl street, North Weymouth, Mill Cove, Norfolk County).
Ecology.
"C. broegeri" occurs together with lampshells "Sunnaginia imbricata" and "Eccentrotheca kanesia", and 
the agnostid "Serrodiscus bellimarginatus".