Chicken fat clot is

ref Robbins 9/e p125 At autopsy, postmoem clots can sometimes be mis- taken for venous thrombi. However, the former are gelati- nous and due to red cell settling have a dark red dependent poion and a yellow "chicken fat" upper poion; they also are usually not attached to the underlying vessel wall. By contrast, red thrombi typically are firm, focally attached to vessel walls, and contain gray strands of deposited fibrin