Inclusions in Polish amber are, in short, a trace of life from the period of time when the liquid resin was coagulating, over 40–60 million years ago. Inclusion can be called everything that is inside an amber and was not resin. Thus, it will include bubbles of air, water, pyrite shells, earth and also plants (twigs, sticks, tree bark) and animals. The latter are called organic inclusions.
In an amber trap fell usually small animals, under 1 cm big; larger organisms were able to get out of resin.
In inclusions dominant organisms are insects (90%), while the rest are arachnids and other animals, such as bugs or myriapoda. Among insects the most are flies, one can also encounter hymenoptera (ants, beetles, hemiptera). Among arachnids rarely can scorpions be found. However, the most precious specimens are undoubtedly vertebrates.
The most valuable inclusions are ambers containing lizards. Throughout the world, only two such pieces have been found – one discovered in 1891 is stored in Göttingen (4.2 cm), the other one was found in 1997 in Gdańsk (3.7 cm) and it is in private hands. Besides, a few traces of legs of small mammals, some hairs of theirs and some bird feathers have been found. Animal inclusions give us opportunities to discover samples of prehistoric DNA.
Inclusions are present in contemporary jewelry, both silver and golden of various forms, simple and sophisticated. Such jewelry is always much more costly, as it is accompanied by an aura of individuality, uniqueness, mysteriousness. Polish amber lumps containing inclusions have always been treated in a special way and had application to exceptional, prestigious objects, and it has not changed. At present they are sought, widely acknowledged, admired, and constitute objects of study. They have been valued and searched for by natural history museums, research centers as well as artists and collectors all over the world. They are one of the kind, objects of research so durably protected by nature.