some similarities to us in order to be as technically advanced as us.
If they used sonar, then it would have to be as good as our eyesight in order for them to be successful. That would essentially be the same as them having eyes. In other words, a being must be able to visualize the world around it in three dimensions.
It must have dexterity of it's limbs in order to build and use tools. That necessarily means fingers or extremely developed tentacles.
If you just stop and think what it would take to be technologically advanced, you'd realize that a minimum of things must be a certain way.
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"Moderation in temper is always a virtue; but moderation in principle is always a vice." -Thomas Paine
The Constitution is not an instrument for the government to restrain the people, it is an instrument for the people to restrain the government."