"It was the same name which the humans used for themselves," she said, "to distinguish them from other humans, but as we are now the only group to bear the name, it has become the name which distinguishes us as a life-form from all others. The first of us kept it because they were told that was what they were, we have no changed it becuase it seemed unecessary, being that, as a noun, of requires only to be an arbitrary label."<br/><br/>She liked his thinking, he was right, of course, at least mostly.<br/><br/>"They are, in a sense interchangable, at a full-body level, though our bodies operate differently," she said, "I could not use my designer's arm without some high degree of adaptation in the connection. Though, you are right, the parts of my body are, well, unimportant, though I do have a certain sentimental attachment to my appearence, and the function it possesses is preferable for me. You are right in assuming a high degree of variation, though, my desinger is a near-perfect sphere with one-metre diameter. It operates sets of distinct limbs remotely."