What do you mean, isn't there a muppet-tribble hybrid at the helmsman station, hiding in or eating the seating?
Spot on. Like all starship chairs, that is a dead alien. Must be an inhabitant from one of the planets in the Squornshellous system. For more info: http://en.wikipedia.org/wiki/Places_in_The_Hitchhiker's_Guide_to_the_Galaxy#Squornshellous
It is the first release of this kit: http://www.round2models.com/models/polar-lights/starship-enterprise/