In 2373, the USS Voyager discovered an unstable interfold layer in the Delta Quadrant, while investigating a series of destructive astral eddies. It was discovered that the layer acted as a spawning ground for the eddies, which would erupt into normal space when they grew large enough. The layer was discovered when the crew sent a probe into one of the eddies, which collapsed back into the layer and took the probe with it. Although the probe could not be detected with sensors, it continued to transmit information on the layer to Voyager.