This is a flying buttress. Redwoods grow back into themselves as they expand into space, and this flying buttress is a limb shot out of that small trunk, going back into the main trunk and fusing with it.
Las secuoyas crecen devuelta sobre sí mismas cuando se expanden al espacio y este contrafuerte aéreo es una rama que sale de un tronco pequeño, que vuelve al tronco principal y se fusiona con él.