War of the Worlds Unicorns vs Mermaids

It's another lovely day on Ocea, a planet entirely inhabited by mermaids. Suddenly, a huge metallic unicorn lands on the seafloor! Sol, a mermaid scientist, determines that it is an alien spaceship. A neon pink laser blast tells her these creatures do not come in peace. Hundreds of armed unicorns wearing bubble helmets swarm out of the metallic unicorn ship. An epic battle takes place between the mermaids and the unicorns. Can the mermaids discover the unicorns' weakness in time to save their planet?