Question

current attempt in progress
incorrect. these are tendon like cords that connect the tricus components of the internal heart.
which structure is visible on the surface of the heart?
papillary muscle
chordae tendineae
interventricular septum
pectinate muscle
left auricle

Explanation:

Chordae tendineae are inside the heart, not on the surface. Papillary muscles are also internal. The interventricular septum is an internal partition. Pectinate muscles are in the atria. The left auricle is visible on the heart's surface.

Answer:

left auricle