What is body symmetry? has the symmetry of the adult sea urchin evolved or change since the pluteus larval stage? if yes, how?

Symmetry is the balanced distribution of duplicate body parts or shapes within the body of an organism. The symmetry of the adult sea urchin evolved or change since the pluteus larval stage. The adults are recognizable by their (usually five-point) radial symmetry, and include such well-known animals as sea stars, sea urchins, sand dollars, and sea cucumbers. 

An autotrophic protist - they can perform photosynthesis and mainly consist of unicellular algae. they can be divided into number of systematic group according to the shape of their cell and the type of photosynthetic pigments they use.