Think of an animal, like a snail, building its shell like someone who is building a brick home. Each colored piece seen here represents calcium carbonate, an essential molecule or brick, which many marine animals use to construct their homes.
Ocean acidification reduces the amount of building material, or calcium carbonate, available to animals in the ocean.
So while our snail is stacking those bricks, some of them are being taken away. It takes more time and energy for our snail to build its shell and the shell becomes weaker.
Throughout the narrative, the vocabulary is designed to match the visualizations and videos as closely as possible. Content and timing of the script need to mirror what your audience is seeing to avoid cognitive dissonance and distraction.
The causal link of observing how OA impacts an animal building its shell reinforces the understanding of larger system impacts to the ocean food web described later in the narrative.