Bats come in different sizes and shapes

The weird-shaped flaps actually help project the sound they emit, like nose-megaphone. The diversity in shape only reflects the diversity in types of calls bats emit when echolocating, depending on habitat, prey type, and more! In many cases, bats have evolved concurrently with insect prey which have learned to detect the sounds of their echolocation, which puts impetus on them to be continually changing the way their calls sound as well

Source: @josegabrielwildlife