For semester exam preparation, consider this situation: an elongated soft-bodied echinoderm lies on the sea floor and has reduced ossicles. The correct conclusion is:

Sea cucumbers belong to Holothuroidea. They are elongated echinoderms with leathery bodies and reduced skeletal ossicles compared with sea urchins. This MCQ belongs to the Holothuroidea topic in Animal Diversity-I and is written to test concept understanding rather than memorized wording.