Two Wyndham winter dippers are trying to find ‘Nemo’.

Navanya Matthews and Rea Haare brave the chill for the weekly Winter Dip events off Altona Pier and came across a sunken treasure earlier this month – a knife engraved with Happy 21st Nemo.

“We go to the Winter Dip every Wednesday and Saturday and one of the members dropped their keys,” Ms Matthews said.

“Rea was helping to look for the keys and found this knife under the pier just peeking out of the sand for her to see.

“We’ve been told that the knife is quite a good quality one and it looks like it was a special gift and we would love to find the owner.”

Ms Matthews took her search to local residents’ group Facebook pages but to no avail.

“It’s likely someone dropped it while fishing off the pier but people have come up with a lot of theories about the story behind the knife filled with murder and mystery,” she said.

Anyone with information can contact: 0415 722 820.