What are the many little branches of the respiratory system?

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

The sea slug that considered to be a photosyntheesizing animal

Based on their relative positions in the periodic table, which two elements would have the same number of valence electrons?