Trilobites are well known as an extinct arthropod taxa from the Palaeozoic Era. Worldwide palaeontologists studied them for more than hundred years and described many forms and types. My study is concentrated on their structures and ontogeny and main target is to analyse their life as well as feeding habits based on morphology. During my study I am trying to applicate microscopy analyses on two extraordinary preserved trilobites: on ontogenetic stage and cephalic spine of another taxon. The exceptionally preserved ontogenetic stages of Cyrtosymbole? sp. have been discovered in the locality near Brno. Material, preserved in muddy limestone, contains several protaspid specimens as well as disarticulated meraspid cranidia and pygidia. Thanks to SEM we are able to study microstructures and morphology. The protaspides are approximately 1 mm long and 0.9 mm wide, sub-ovoid in dorsal view. Protocranidium is sub-trapezoidal, with glabella reaching ca 80 % of protocranidial length. Trunk is semicircular in outline, composed of at least four segments. The morphology of the protaspides is typically proetoid and corresponds to a benthic post-metamorphic stage. This material represents the first Famennian ontogenetic stages of trilobites which has been discovered at the area of the Bohemian Massif and it represents the youngest known ontogenetic trilobite stages from the Czech Republic. Other object of my study is the cephalic spine of very rare trilobite Ancyropyge sola have been found for the first time in Czech Republic and its structure is poorly known based on Canadian finds. Thanks new microscopy photographs (ESEM) we can interpret its right screw-structure.