Police officers stumbled across a makeshift dog's grave during a forensic search of bushland on the NSW mid-north coast, an inquest into the disappearance of William Tyrrell has heard.

Key points: William Tyrrell disappeared from Kendall on the NSW mid-north coast almost five years ago

William Tyrrell disappeared from Kendall on the NSW mid-north coast almost five years ago Despite a massive police search, no light has been shed on what happened to the toddler

Despite a massive police search, no light has been shed on what happened to the toddler Police were tipped-off that cemetery grave stones had been moved, but it was a false lead

The grave was among several red herrings that cropped up during an extensive search for the toddler, who was last seen wearing a Spider-Man suit when he vanished from his foster grandmother's home in Kendall almost five years ago.

The inquest heard the search for William Tyrrell was a massive police operation involving many officers, who were instructed to look for anything out of the ordinary.

It heard the wooden cross was marked "2014" — the year William Tyrrell vanished from his foster grandmother's home.

"It struck my curiosity … there was blue plastic so we carefully dug around it … and then we unwrapped the plastic and discovered the corpse of a small dog," Senior Constable Grant Hollis said.

Tombstones moved

Senior Constable Hollis also told the inquest about a tip off police received during their search, that had to be investigated.

"We got third-hand information about someone who had been in a cemetery and had moved certain tomb stones around," he said.

"It was information that was possibly related to the matter — he showed us a headstone that could possibly be related, so the cadaver dog attended."

Those investigations brought no information relevant to William Tyrrell's whereabouts, the inquest heard.

Police also found a cubby house, with a hand-painted sign reading "Cooper's Cubby", as well as the sole of a small shoe, and a structure that resembled "a shrine of some sort".

Police were given a photo of William Tyrrell and told to search for "anything out of the ordinary". ( AAP: Dan Himbrechts )

The hearing before the NSW Coroners Court in western Sydney heard how officers were given a photograph of William Tyrrell and were instructed to raise the alarm if they found anything unusual.

Senior Constable Kris Rattenbury described the police operation that took place around Benaroon Drive in Kendall last year as "the biggest I've ever seen".

"Obviously the media attention this case has received, everyone wants to find out what actually happened," he said.

"We were searching for clothing that matched that description and human remains … so anything out of the ordinary.

Counsel Assisting, Gerard Craddock yesterday told the inquest it was most likely William Tyrrell was abducted by a stranger and driven away from Benaroon Drive in a car.

The inquest, before Deputy State Coroner Harriet Grahame, will resume in western Sydney on Monday before it moves to Taree Courthouse on August 19.