mysterious fibre balls

Believe it or not, we are still on the topic of seagrass - this time in South Australia. While visiting relatives at Middleton (near Victor Harbour), Jane and I took a little time to explore some local beaches.

The beach at Middleton is a beachcombers' paradise and has some really special beachcombing treasures.

My favourite Middleton treasures are commonly known as fibre balls. These tightly woven balls of fine, hair-like fibre can be as large as a cricket ball (although they don't bounce, I am sure that they are used for beach games).

These balls are really common but few people seem to know where they come from or how they are formed.

a fibre ball on
Middleton beach
(click thumbnail for full image)

children playing with a
larger seagrass ball
(click thumbnail for full image)

The answer is offshore. Just beyond the breakers are seagrass meadows composed mainly of a seagrass commonly known as tapeweed (a number of seagrasses belonging to the genus Posidonia). Fresh tapeweed leaves can be seen in the fibre ball photograph shown here.

As with other seagrasses, tapeweed has proper roots, stems and leaves. A close look at a tapeweed leaf will show that it has veins.

These veins are the clue to the mystery of the fibre balls - in fact, that's what fibre balls are made from. When tapeweed leaves are shed, the softer material rots away to leave the veins behind.

The waves roll these hair-like fibres into long sausage shapes or the perfectly round fibre balls. The stems of other seagrasses and other materials are also matted together in larger balls and sausages that are found on Middleton beach. These seagrass balls can be as big as a soccer ball.