Distribution of extant populations of Quadrula mitchelli (false spike)

ligament hardens, but while this time may be very short in air, it can be very long for animals continuously submerged. Shell condition data are useful to assess species presence in a stream, but within lentic systems, and especially shells rapidly buried in mud or sand, shells may remain sufficiently protected that condition becomes a poor indicator of population presence. Understanding how quickly mineralization/fossilization occurs is another question requiring future investigation.