He said its length was "a metre probably".
He did not touch it as he was not sure if had bacteria on it – but it did not smell.
It looked like it was "slimy and squishy and stuff like that".
"I tried to convince my dad to keep it in a plastic bag, but he wasn't really in on that idea.
"I think it's because adults don't really enjoy giant worms in their houses. If I was an adult, I would agree.
"I thought of it as like an amazing discovery and I could not believe my eyes."
He even gave it a name – Dead Fred.
His mother, Jo, agreed on the size.
"I think it's probably about a metre. He was outside in the yard - we've got a bit of an abandoned river bed on the edge of our property - and that's where he was digging around and stumbled upon – in the water - this giant, disgusting worm.
"I suspect it's about a metre long. He got it out with the stick, didn't want to touch it, but was pretty delighted to find it.
"I think it was already deceased when he came across it, so sort of just bobbing on the edge of the water there and he dug the stuck in and pulled it up and then my husband took the photo.
"He didn't take any videos or anything, (he) wasn't overly excited by it … which I just can't believe because as soon as I saw the photo, I just, you know, wanted to be sick in my mouth.
"It is so huge and … it looks to me in the photo pretty slimy, which is pretty gross. I wonder if it could have been floating in the water and if it had taken on some water so it was sort of bloated."
When her son went back for another look on Friday but Dead Fred had gone, potentially having floated off.