Many tissue-dwelling helminths, arthropods and protozoa may be detected in histological sections made from samples collected at post-mortem (or occasionally by biopsy). While it is usually easy to detect “the parasite” in a section, it is sometimes very difficult to make an identification, even to group (e.g. nematode versus cestode versus trematode versus arthropod), or, for protozoa, to genus. Because of this, if helminths or arthropods are thought/known to be present in a tissue or organ, and especially if they are believed to be of some significance, it is very important to try to recover intact parasites (which are relatively easy to identify) before collecting samples for histology.