<p>Recent advances in fluorescent imaging facilitate actualistic studies on organisms used for palaeoceanographic reconstructions. Observations of cytoskeleton organization and dynamics in living foraminifera foster understanding of morphogenetic and biomineralization principles. This paper describes the organisation of a foraminiferal actin cytoskeleton using <i>in vivo</i> staining based on fluorescent SiR-actin. Surprisingly, the most distinctive feature in the organisation of actin in Foraminifera is the prevalence of actin-labelled granules (ALGs) within pseudopodial structures. Fluorescent signal obtained from granules dominate over dispersed signal from the actin meshwork. Actin-labelled granules are small (around 1 µm in diameter) actin-rich organelles demonstrating a wide range of motility behaviours from almost stationary oscillating around certain points to exhibiting rapid motion. These structures are present both in Globothalamea (<i>Amphistegina</i>, <i>Ammonia</i>) and Tubothalamea (<i>Quinqueloculina</i>). They are found to be active in all kinds of pseudopodial ectoplasmic structures, including granuloreticulopodia, globopodia, and lamellipodia, as well as within the endoplasm itself. Two hypotheses regarding their function are proposed: (1) They are involved in endocytosis and intracellular transport of different kinds of cargo; (2) They transport prefabricated and/or recycled actin fibres to the sites where they are needed. These hypothesis are not mutually exclusive. The first hypothesis is based on the presence of similar actin structures in fungi, fungi-like protists and some plant cells. The later hypothesis is based on the assumption that actin granules are analogous to tubulin paracrystals responsible for efficient transport of tubulin. Actin patches transported in that manner are most likely involved in maintaining shape, rapid reorganization, and elasticity of pseudopodial structures, as well as in adhesion to the substrate. Finally, our comparative studies suggest that a large proportion of actin-labelled granules probably represent fibrillar vesicles and elliptical fuzzy coated vesicles often identified in TEM images. Correlative fluorescent electron microscopic observations are proposed to verify this interpretation.</p>