Nature has devised ways for some species to survive together. The association can be a permanent physical joining or simply a long-term relationship.
The association of two or more species is called symbiosis. The term does not always imply a harmonious relationship and sometimes mimicry, camouflage or outright deception is used by one species to survive with or through another.
Good and Bad
Symbiotic relationships can be beneficial to both species, like clown fish that clean anemones in return for food, or harmful in the case of parasites that take food but often inflict disease or illness from malnutrition.
A type of symbiotic relationship that is more positive is when one species shares the food harvested by another species. The term for this kind of symbiosis is commensalism.
Army ants and silverfish share a commensalism type of relationship since silverfish live with and share the food caught by army ants. At times, silverfish will even participate in foraging and food raids conducted by army ants.
While the commensalism relationship between army ants and silverfish seems harmonious enough, it is neutral in that the presence of silverfish is neither beneficial nor harmful to army ants.