Crank and submarine: what they have in common

1. Step 1. Crank — evolved into — Starter motor. It replaced the starting crank.
2. Step 2. Starter motor — uses — Car battery. Power.
3. Step 3. Car battery — is a kind of — Lead–acid battery. Lead–acid.
4. Step 4. Lead–acid battery — is part of — Submarine. Underwater, electric motors run on batteries.

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