we are know about 'Colloid.
It is a particles in solution which is unsalable but till entity in liquid.
Coroid Plexus
Pigmented choroid coat: appears iridescent in the cow or sheep eye owing to a special reflecting surface called the, Tapetum lucidum. this specializes surface reflects the light within the eye and is found in the eyes of animals that live under conditions of low intensity light... not found in humans. Yuri