In which group of bilaterians do you find solid bauplan ? Why is it called so ?

Explanation

The bilaterian.s body plan is the solid bauplan when only one plane that passes through the identical axis divides an organism into two identical parts, it is called bilateral symmetry. It is the principal type of symmetry in the triploblastic animals.
Bilaterally symmetrical animals are more efficient than the other animals in Seaking food locating mates and in avoiding or escaping from predetors, because of cephalization. As a result of cephalization, bilaterally symmetrical animals can sene the new environment into which they enter and respond more efficiently and quickly.