Final answer:
Birds, certain bacteria, and fish are known to harbor tiny magnets within their bodies, helping them in orientation, navigation, and habitat location through magnetoreception.
Step-by-step explanation:
The question relates to organisms known to possess tiny magnets within their bodies. The correct organisms that harbor these tiny magnets include birds, certain types of bacteria, and fish. These biological magnets are often involved in magnetoreception, which is the ability to detect the Earth's magnetic field and use it for orientation and navigation. In birds and fish, this ability assists with migration and in navigating their environment. Magnetotactic bacteria align themselves with the Earth's magnetic field lines, which can be beneficial for finding optimal habitats.