Plastic Covering under carriage under Engine

I have a Mazda 3 and the Plastic that covers the front under carriage under the engine has cracked off. It is the piece behind the front bumper under the engine. Does anyone know if it should be replaced and what the cost would be?
Thanks

It probably wouldn't be a bad idea. It tends to deflect a lot of road debris and keeps the engine somewhat clean, not to mention it helps with the aerodynamics a bit.