CREATE TABLE table_75248 ("common name" TEXT, "protein name" TEXT, "divergence from human lineage  ( MYA ) " FLOAT, "accession number" TEXT, "sequence length  ( aa ) " FLOAT, "sequence identity to human protein" TEXT)

What is the accession number of the protein with the common name Purple Sea Urchin?
SELECT "accession number" FROM table_75248 WHERE "common name" = 'purple sea urchin'
SELECT "accession number" FROM "table_75248" WHERE "common name" = 'purple sea urchin'