When we look at snails and hermit crabs together, we see two contrasting yet complementary designs. The snail is self-sustaining in its shelter-making, while the hermit crab is resourceful in repurposing what others have left behind. Both display adaptability to their environments: land snails can retract deep into their shells and seal the opening with a mucous “door” during drought, while hermit crabs can live both on land and in the shallows, moving easily between different worlds.

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