Were Trilobites Herbivores, Omnivores or Carnivores?
There is no conclusive evidence to rule out any of those possible diets. It seems reasonable to use modern-day crustaceans as an analog, which would lead one to believe that they are predator-scavengers, like most modern crustaceans. However, even among modern crustaceans some are filter-feeders ( barnacles), some are planktivores (most larval crustaceans), some are herbivores (many shrimp species), and some are parasites (copepods, isopods), so it is hard to conclude anything about the diet of the trilobite with certainty. It is even likely that different species of trilobites specialized in different types of diets, with some being omnivores, some being carnivores, some being herbivores, etc. Other possibilities are that they were particle-feeders (likely mixed diet of plant and animal) or filter-feeders (plant, but could have included zooplankton) and even olenimorphs with a symbiotic relationship with sulfur-eating bacteria. See:
