The majority of morphological abnormalities reported for elasmobranchs are cases of bicephalia. This contribution describes the third confirmed case worldwide and the first in the South Atlantic of diprosopus tetrophthalmus (craniofacial duplication) in a foetus of blue shark. Prionace glauca (Linnaeus. 1758). https://macorners.shop/product-category/birthstone-gift-box/