Nessa (Pokémon) was performing her first mermaid routine for her viewers. She eventually sat down on a mechanical shell that closed with her inside.
Taking a break, Nessa took a rebreather from underneath, but realized there wasn't enough air to sustain her.
Panicking, she hit the shell repeatedly, but it would only open after some time had passed. With no other way to breathe, she quickly blacked out.
Her body settled on the shelf. Her first performance was slowly becoming her last if someone didn't notice something was wrong.