Wildlife Spotting

Another student and I were walking home, when I noticed a white shape in our ditch (a stagnant form of water). Upon picking up the shape, we noticed it was a cylinder shape rounded off at both ends. It was slimy to the touch and clearly had a yolk in it, upon touching it, it would bend beneath our fingertips (suggesting that either the water had softened it, or it failed to calcify.). There were trees around the egg, but none close enough to have dropped it, our grass is too thick for it to have rolled over into the pool (it has quite a bit of weight to it as well, so that was ruled out too).