The statement on the existence of the organisms with "negligible senescence" is based on the supposition that the probability of their death as adult does not change with aging. However, the direct observations which could either confirm or reject such suggestion are absent, and it is impossible to obtain them for the majority of the "non-aging" organisms. The data on the mortality of the European pearl mussel living in natural environment show that despite the features of "negligible senescence" (continuous growth, longevity, capacity to breed during the entire life), the probability of death increases with aging. Whereas only few individuals approach the age of 90-100 years old, vast majority dies being younger than 50 years old. This fact, as well as gaps in the substantiation of the concept of "negligible senescence", indicates that this "phenomenon" does not exist.