Lithological-paleoecological study of the Mid-Upper Carboniferous reef limestones from the section «Verkhnie Vorota» on the Shchuger River revealed the complex of green phylloid algae Ivanovia tenuissima Khvorova, Eugonophyllum konishi Kulik, Anchicodium gracile Johnson, which are directly involved in the construction ofbuildup frameworks. Problematic Tubiphytes, rare cyanobacteria Bevocastria sp., dasiclads Clavaporella sp., Pseudoepimastopora cf. likana (Kochansky et Herak), Pseudoepimastopora sp., Asphaltinella cf. horowigi Mamet et Roux, phylloid Neoanchicodium sp. and red Ungdarella uralica Maslov, Komia sp., Flugelia johnsoni (Flugel) algae were associated with them. The revealed algal complex indicates the existence of a shallow warm sea with good bottom illumination and weak water movement.