Very close similarities between the fossil generaCallimothallusDilcher, 1965 andMicrothallitesDilcher, 1965 and recent representatives of the green algaeUlvellaP. L. & H. M. Crouan, 1859, seem to rule out the assumption that fossil, disciform and radiate palynomorph microfossils are representatives of microthyrioaceous fungi. On the basis of the morphology of fossilUlvella, a model of the general morpohlogy of encrusting, palynomorph algae is constructed. The model includes 5 morphological characters that may only be applied to encrusting life-forms and in particular not to planktonic algae. These characters, therefore, in future palynological research may serve to distinguish benthic algae from planktonic algae. A new fossil alga,Ulvella nannaesp. nov. is described.