This creature is a waterdweller that somewhat resemble a fish. It lives in the retreating oceans of a planet orbiting a star that is reaching its red giant stage. The planet is now experiencing very high levels of radiation and life is becoming extinct...
The creature is a photosynthetic animal so it needs to live close to the surface of the oceans but they lay eggs at the bottom of the oceans to protect their youngs. The youngs eventually develop a strong armour once reaching maturity and lose their fins.
The grownups are basically rocks, they do not have the ability to move any appendages since their thick and solid exoskeleton. They have the ability to move around thanks to a bio-MHD
in the bioMHD the electric current is passed thanks through stacked cells like those of an electric eel.
How can I generated the magnetic field to push the water through?