From Spanish piedra (“stone”), from Latin petra, from Ancient Greek πέτρα (pétra).

What is a Piedra?

Piedra, which means "stone" in Spanish, is an asymptomatic superficial fungal infection of the hair shaft. In 1865, Beigel first described piedra in The Human Hair: Its Structure, Growth, Diseases, and Their Treatment; although, he may have been describing Aspergillus infection.

What is Senderos English?

Wiktionary. sendero. noun. a trail for the use of, or worn by, pedestrians.