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A particular race of Aliens with Forehead Ridges may all have a culture like that of medieval Japan, or one based entirely on music, but you will very rarely find more than one culture per species.
(The Vulcans and Romulans of Trek fame are a rare exception.)Because of the similarity (or at least comprehensibility) of cultures, Earth Humans can have far more complex and intimate relations with Aliens with Forehead Ridges than with Really Aliens.
It would be expecting much of anyone to guess that an oyster were alive if he came across one (for the first time) with a closed shell.
In general, Aliens fall into two distinct groups, REALLY ALIENS and ALIENS WITH FOREHEAD RIDGES.1) Really Aliens are truly unearthly. The occasional intelligent bear or radish may also appear, or practically anything else.This is partly because it is not clear what we would fight them over, and partly because they may have an alarmingly high TECHLEVEL, making war with them a dangerously one-sided proposition. See COSMIC BACKGROUND HISTORY.2) Aliens with Forehead Ridges.Much more common - especially in HOLLYWOOD SCIFI - than Really Aliens, these are species that look almost exactly like Earth Humans, except for some distinguishing visible feature such as, well, forehead ridges, or odd-shaped ears, or whatever.Or what if a drop of water were trickling down the trunk of the tree?The water in motion would be alive, but the motionless tree trunk would be.