Unusual creatures that puzzled Timaru beachgoers are likely to be "spoon worms" according to a Dunedin scientist.

Hundreds of the marine life-forms were scattered along Caroline Bay, lying along the sand, and caught in the debris that has washed up on the bay in recent floods.

The creates, 4-15cm long, move when touched, are quite flexible, and have proved tempting morsels for dozens of seagulls.

Dr Brian Paavo, of Benthic Science Limited, who studies animals on the seafloor, said from the photos, the creatures looked like echiuran, more commonly known as spoon worms because of their spoon-like tongues which scrape mud off the sea floor.

"They are most certainly not slugs. Slug would have a very clear bilateral symmetry where one side looks like the other. With these, you can't tell left from right."

The most certain way to find out would be to cut one [of those creatures] up lengthwise down the middle and take a look at the insides. It should have some very distinct anatomical features, he said.

The radial symmetry of the creatures rule them out from being slugs and geoducks.

Suggestions from readers have so far included:

*beche-de-mer, also known as sea cucumbers,

*priapulid worms (also known as penis worms), 

*sea slugs, some of which can be toxic,

* ''gooey-ducks'' or ''geoducks'' although the reader could not confirm the spelling,

*Sipunculid or peanut worms, and

*echiurans or spoon worms.

- © Fairfax NZ News