Vertebrates share similar embryological developmental stages as depicted in the illustration above. certain structures during development appear on all vertebrates. which structure does not appear on all vertebrate embryos?

When new rock is added to an oceanic ridge, the magnetized strips on either side of the ridge are evidence of sea-floor spreading. this is because the rocks on the two sides of the ridge o are equal in width and in polarity are polar opposites oare magnetized vary in width but are equal in polarity