FIGURE 4. Ohesaare hardground samples, late Pridoli, Silurian, 1. Upper surface, showing patchy distribution of Trypanites borings and very low encrustation density (TUG 1373-1). 2. Upper surface, showing high microconchid (mc) encrustation density with high Trypanites density (TUG 1373-2). 3. Cryptic roof of a hardground ledge showing high encrustation density (TUG 1373-3). 4. Upper surface showing uneven surface relief and very low encrustation and lack of Trypanites (TUG 1373-4). Abbreviations: ant- Anticalyptraea calyptrata, br – sheet-like trepostome bryozoan, cr – crinoid holdfast, mc – microconchid, omc- overgrown microconchid (with open aperture). Diameter of the coin is 17 mm.