Abstract On average, sand particles larger than 300 μm have at least one large smooth facet on their surfaces on which the epifloral food of meiobenthic copepods is distributed as a coarse-grained ecological resource. Sand particles smaller than 300 μm have irregular surfaces composed of pits, faults and encrustations in which food organisms are distributed in a fine-grained manner. The cooccurrence of two ecological grains of food resources in sediments with a mean particle diameter of 200 μm helps to explain the anomalously high diversity of animals in these sediments because it allows the co-existence of selective and non-selective epistrate feeders.