  The Posner molecule (calcium phosphate trimer), has been hypothesized to
function as a biological quantum information processor due to its supposedly
long-lived entangled $^{31}$P nuclear spin states. This hypothesis was
challenged by our recent finding that the molecule lacks a well-defined
rotational axis of symmetry -- an essential assumption in the proposal for
Posner-mediated neural processing -- and exists as an asymmetric dynamical
ensemble. Following up, we investigate here the spin dynamics of the molecule's
entangled $^{31}$P nuclear spins within the asymmetric ensemble. Our
simulations show that entanglement between two nuclear spins prepared in a Bell
state in separate Posner molecules decays on a sub-second timescale -- much
faster than previously hypothesized, and not long enough for super-cellular
neuronal processing. Calcium phosphate dimers however, are found to be
surprisingly resilient to decoherence and are able to preserve entangled
nuclear spins for hundreds of seconds, suggesting that neural processing might
occur through them instead.
