Först måste vi överväga att "Sphere" är mindre Hard SF och mer mjuk SF, thriller, flygplats roman och så. Så går allting (inklusive bipedala, engelsktalande lilla gröna män).
Slutligen bör man sluta vara antropocentrisk medan man läser SF (minst hård SF), utomjordingar (även människor från framtiden) tänker inte eller gör saker som oss. Det finns också olika typer av rymdfarkoster som ännu inte uppfunnits . Vår nuvarande rymdfarkost baseras på kemisk framdrivning och bristfällor (förutom Shuttle). Men den nyligen utvecklade solseglingsbaserade rymdfarkoster är radikalt olika i design.
When the spaceship was first discovered, it was easily determined that this was an alien spaceship. It was beyond the technology possessed by any of the human nations at that time. So, perhaps a spaceship which was radically different from human spaceships, even to the casual observer, was needed to be described. Humans spaceships don't have fins, this one has. Thus, it may be essential to the plot.
Furthermore, when the spaceship was inspected from the inside, it contained many features which were never explained at all. This implies that the builders were far more advanced than us. At one point, it was speculated that the ship may be a sleeper-ship or a time-traveling ship. As, humans are far from inventing anything remotely close, maybe the fins serve some purpose and human can't understand it because they do not have the fundamental knowledge.