Inside these eggs are one of Australia's most venomous animals

A surprise clutch of eastern brown snake eggs "gifted" to a New South Wales snake catcher at the start of the year are "doing well".

Sean Cade, owner of Australian Snake Catchers, became a surrogate mother to "23 perfect eggs" at the beginning of the year, when a gravid snake laid them in his bag overnight.

At the time Mr Cade described the event as "rare".

Speaking to 9news.com.au today, Mr Cade is happy to report the eggs are developing well and slated to hatch "sometime in March".

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He said a friend is currently acting as a stand-in aunty.

"She has got the incubator," he said with a laugh.

"She's misting them. Snake eggs are leathery and soft, not rock hard like a bird egg, so they need moisture".

Mr Cade added in the wild eastern brown snakes leave their eggs once laid, with 16 considered an average clutch size.

Of the 23 eggs laid about six look like they're going hatch.

"Six is good, if I can save one of these eggs that's a good result in my book," he said.

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Eastern brown snakes are considered Australia's second most venomous land snake.

Mr Cade said the baby snakes will be too fragile to milk for the state's anti-venom programme when born.

So, instead they will return to the wild.

"That's where they belong," he said, explaining the baby snakes are just as venomous as their adult counterparts.

"It's unfortunate how I came to have them in having to rescue the mum in the first place.

"They're an important part of the ecosystem."

Australia is nearing the end of snake season, which runs from around mid-September to March.