These plants grow naturally on the side of trees and grow a unique protective shield to keep the roots safe. It is normal for the shield to brown as a new one grows. 

Care:

Light: Low to medium filtered light

Water: Water soil when the top half dries. Well draining soil will go a long ways towards the health of your plant. 

Temps: Best between 65 and 75 degrees. 

Pets: Safe for pets. https://www.aspca.org/pet-care/animal-poison-control/toxic-and-non-toxic-plants/common-staghorn-fern