A learner makes a note: a sea star larva swims with right and left sides before developing into a radial adult. The missing scientific idea is:

Echinoderm larvae are bilaterally symmetrical, while adults become pentaradial. This supports the evolutionary relationship of echinoderms with other bilaterian animals. This MCQ belongs to the Echinodermata topic in Animal Diversity-I and is written to test concept understanding rather than memorized wording.