Name two living organisms whose shapes have five-fold rotational symmetry

Rotational symmetry is radial symmetry which means that the shape is the same after several rotations. In five-fold rotational symmetry the number of distinct orientations in which the object looks the same is five. 
Living organisms whose shapes have five-fold rotational symmetry are sea stars (starfish) and sea urchin. They can be mapped onto itself through rotation about a central point by an angle of 2π/5. 

A- a reduction in biodiversity