Marine fish have a planktonic larva. Either the eggs will be sticky and laid on the shore, e.g. sand eels, or for those living further out at sea 1000s of transparent eggs will be released into the water. The latter are the ones seen here. Only about 20-30 appeared in an autumnal sample and must have been brought in by the tide. One of the eggs has a developing embryo. Each egg has a strong outer chorion coat and is around 1 mm in diameter. Distinct in the photo is the presence of a drop of oil on the developing egg. Along with the yolk within the chorion the oil will also be consumed as food although it probably helps with buoyancy.