What are good alien-themed gifts that do not look childish?

Good non-childish alien-themed gifts usually work best when they feel like design objects, science-fiction collectibles, or space-inspired home goods rather than novelty toys. Strong picks include: an elegant alien/space art print, a premium UFO desk lamp, a subtle Area 51-style enamel pin or cufflinks, a high-quality sci-fi book edition, a meteorite or tektite specimen, minimalist alien socks or apparel, an alien-themed board game for adults, or a tasteful mug/barware set with a restrained design.