Abstract: Non-mineralized animal tissues may be fossilized in exceptionally taphonomic conditions. Stable non-mineralized tissue fossils may be preserved either as organic remains or by replication in authigenic minerals. The most commonly occurring diagenetic minerals associated with exceptional preservation are pyrite, carbonates and phosphates, among which phosphates precipitated early enough to replicate subcellular details. Non-mineralized tissues, both volatiles and refractories, can be permineralized, pseudomorphed and molded by these authigenic minerals. To find the mechanism of non-mineralized tissue fossils, paleontologists and geochemists should cooperate more closely and do further research.