Strange Things on the Beach

I've often noticed clear jelly-looking crescent shaped blobs washed up on Australian beaches and the shorelines of coastal lagoons and lakes, but never really thought about them much beyond "they must be bits of jellyfish - or something"

Mystery blobs on the tideline

The blobs are actually thousands of moon snail (Conuber sordidus) eggs embedded in a matrix of mucus and sand. The female snail lay her eggs in a single line within the sandy matrix, which then takes on water and forms the crescent-shaped jelly substance. The egg sacs break up in the water after a few days, releasing planktonic larvae from the eggs.

Not so much of a mystery now

The egg mass can grow up to five times larger than the snail which laid it, growing between 5cm and 10cm in length. These ones were photographed from the boardwalk around Merimbula Lake, Southern New South Wales.

A conuber sordidus egg sac in the water