'Forceful,' 'acrobatic,' 'muscular,' 'raw,' even 'gritty' are usually the operative adjectives to describe the architecture of Thom Mayne (2013 AIA Gold Medalist) and his firm, Morphosis. But not 'refined.' Yet the Perot Museum of Nature and Science, which opened in Dallas last month, seems surprisingly restrained for a building by the Los Angeles firm. With its pale, crinkly precast-concrete panels enclosing a cubic volume, it appears rather sedate from afar. At the same time, there is a raw energy in the way the calm cube erupts from a craggy free-form plinth covered with shards of rock and local plants.