The population of secondary craters - craters formed by the ejecta from an initial impact event - is important to understand when deriving the age of a solid body's surface. Only one crater on Mars, Zunil, has been studied in-depth to examine the distribution, sizes, and number of these features. Here, we present results from a much larger and older Martian crater, Lyot, and we find secondary crater clusters at least 5200 km from the primary impact. Individual craters with diameters >800 m number on the order of 104. Unlike the previous results from Zunil, these craters are not contained in obvious rays, but they are linked back to Lyot due to the clusters' alignment along great circles that converge to a common origin. These widespread and abundant craters from a single impact limit the accuracy of crater age-dating on the Martian surface and beyond.