A replica gun has been found on day 16 of the search for William Tyrrell's remains on the NSW Mid North Coast.

It was discovered in cleared bushland beside Batar Creek Road at Kendall.

A yellow evidence marker with the letter "B" was placed near the firearm, while specialists photographed the piece of evidence.

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While it's mysterious, it's unlikely to be linked to the missing child.

In a statement, police said it's "not related to Strike Force Rosann", which was set up to investigate the boy's 2014 disappearance.

The replica weapon will however be taken away for forensic testing.

So far, 32 items of interest have been collected, including animal bones, many pieces of material or fabric, and plastic bags.

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While nothing has stuck out on face value, detectives are hoping for a break through from the lab.

Dozens of officers are now in their third week of picking through mud and sifting through soil at the search site, which is about a kilometre from the home where William Tyrrell was last seen.