Why couldn't Moana see the spiral?

Question

Moana and Maui's quest is to restore the Heart of Te Fiti to its rightful place in the spiral but when she arrives at the island, the spiral isn't immediately visible.

Later in the film it becomes evident that

Te Ka is in fact Te Fiti when she sees the spiral on its chest.

But on multiple occasions we see Te Ka in pretty good detail and the

spiral is nowhere to be seen.

Was the climatic battle (and specifically the 'whale splash') necessary to the restoration since the spiral isn't visible until shortly after that?

It would have been some nice foreshadowing to see at least some hint of the feature earlier in the movie which makes me think that its absence was purposeful. Are we supposed to see her outer skin as an analogy for emotional armour, that had to be removed before the Heart could be restored?

Answer 1

According to the film's junior novelisation, the spiral was covered under layers of cooled lava. It wasn't until the climactic fight (which resulted in multiple layers being smashed off, at the cost of Maui's hook) that the spiral was finally revealed.

No longer sure what to do, Moana took a deep breath to calm herself and listened for her voice inside. She turned and saw Te Kā looming over Maui, volcanic lightning flashing all around them. And then she spotted something on Te Kā’s chest. A glowing spiral covered up by cooling lava. Moana looked over her shoulder at the empty crater where Te Fiti should be.

“The spiral…” she said, looking down at the heart in her hand. Its glow brightened with her every step and she looked to the ocean. Moana knew what she had to do.

_{^{Moana - Junior Novelisation}}