Since the discovery of bacteria researchers have primarily studied bacteria as organisms that enter the body individually and only then accumulate or agglutinate, creating what is known as biofilm.
If the density current is sufficiently hot the particles will agglutinate and weld at the surface of sedimentation to form a viscous fluid, this is primary welding.
A consequence of this is that - at certain concentrations - a viral suspension may bind together (agglutinate) the red blood cells thus preventing them from settling out of suspension.