The toads' destination: their birthplace in the Roxborough Reservoir, which once provided drinking water to Philadelphians and is now preserved as open space in the city's park system.
Because they are preserved in the Gale crater still today, it implies that the water there had relatively little acidity -- that is, it was fresh water, like the water you'd find in most ponds or lakes on Earth today.
For example, although the findings concerning water are exciting, the presence of water may mean that organic molecules indicative of life were not well-preserved, Grotzinger said.