I found this egg shaped rock on the beach at Hornsea in East Yorkshire. It is very egg shaped, slightly flattened but with a very distinct zig zag mark all the way round the tapered end which closely resembles the marks that a chick makes when emerging from a hen's egg. Could it be a fossilised egg, if so what kind of creature.
The beach system on the Holderness produces many different shaped rocks because of the conditions the rocks are deposited into.
During the last ice age 14000ya aprox when the ice melted it deposited rocks and boulder clay on to the Holderness coast, the rocks are known as erratics and move about in the beach system getting rolled about and abraded by other rocks and sand.
If you stand next to the waves and listen - you can actually hear the rocks rumbling around and colliding.
I once found a brick like your 'egg' in shape with the three holes down the middle of it near Mappleton but you can find these occasionaly all along the Holderness.