Pseudofossils

Martian meteorite found in Antarctica in 1984

thumb|Concretions in Torysh, Western [[Kazakhstan]] thumb|Concretions with lens shape from island in Vltava river, Prague, Czech Republic thumb|Marlstone aggregate concretion, [[Sault Ste. Marie, Michigan, United States]] A concretion is a hard and compact mass formed by the precipitation of mineral cement within the spaces between particles, and is found in sedimentary rock or soil. Concretions are often ovoid or spherical in shape, although irregular shapes also occur. The word concretion is borrowed from Latin , itself derived from concrescere , from con- and crescere .

demonstration of metallic salts crystallization

Pseudofossils are inorganic objects, markings, or impressions that might be mistaken for fossils. Pseudofossils may be misleading, as some types of mineral deposits can mimic lifeforms by forming what appear to be highly detailed or organized structures. One common example is when manganese oxides crystallize with a characteristic tree-like or dendritic pattern along a rock fracture. The formation of frost dendrites on a window is another common example of this crystal growth. Concretions are sometimes thought to be fossils, and occasionally one contains a fossil, but are generally not fossils

possibly earliest multicellular lifeforms

pseudofossil