Conversely, rarer events provide more information when observed. This would tend to preserve rarer morphs from extinction. Quadruplets are much rarer than twins or triplets. Such churches are much rarer and generally younger. Some STT cards are rarer than others. Additional variants can be found on rarer models. Much rarer than the typical tonsil stones are giant tonsilloliths. Homogeneous nucleation is much rarer than heterogeneous nucleation. Cholangitis and gallstone pancreatitis are rarer and more serious complications from gallstone disease. This use of alternative, common kanji in place of rarer ones was called . Many are made of rarer and softer materials. U1b has a similar spread but is rarer than U1a. Midnight Blue was an even rarer alternative colour. Attaining adulthood is much rarer for fish. Successful clemency applications are thought to be even rarer.