This their second album, whose sound was completely different from their debut, became another unexpected commercial success, with the hit single "Escuela de calor". Tracks included in this record such as "Semilla Negra" introduced the first hints of what would soon become their signature contribution: Latin rock based on a highly intellectualized basis (front man Santiago Auserón holds a degree in Philosophy and is known for lengthy answers in flourishing vocabulary) but, notwithstanding, aimed at the streets and addressed to the general populace; this popular turn became the standard in Spain after them, but was a virtually unknown territory back in the day when Radio Futura started defining its boundaries.