The brother of a Sydney surfer killed in a shark attack has paid a touching tribute to his twin, just days after he was laid to rest.

Mercury Psillakis, 57, was fatally mauled by a 3.6-metre great white while surfing off Long Reef Beach at Dee Why on Sydney’s Northern Beaches on September 6.

He was killed a day before Father’s Day and leaves behind his wife, Maria, and daughter, Freedom.

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Mercury was laid to rest at a service at Archangel Michael Greek Orthodox Church in Crows Nest on Thursday, with twin brother, Mike, saying a part of him had died too.

“Did you know that identical twins for the first six to 12 days of their lives from conception are one? Then the cells split in two,” Mike posted to social media on Saturday.

“Originating from a single fertilised egg that splits into two embryos early in development, resulting in two individuals who share the same genes and are always the same sex.

Mercury Psillakis, 57, was fatally mauled by a 3.6-metre great white while surfing off Long Reef Beach at Dee Why. Credit: Facebook

“I take solace in knowing that when Merc died, a part of me died with him. But more importantly, a part of him lives through me, helping me to carry his flame as long as I live.”

Only one day after the funeral, Mike, who owns a shop that makes custom surfboards, went back in the ocean for the first time since his brother’s attack, saying it was “good to get the monkey off my back”.

“My first wave was undoubtedly gifted to me from my brother Mercury,” he said.

“It was a freak wave in substandard conditions and I just paddled out.

Mercury Psillakis had only been surfing at Dee Why for 30 minutes beach when he was attacked. Credit: ai_yoshi/Getty Images/iStockphoto

“Yesterday was hard. Laying my brother... down for his last eternal wave, but in the midst of the pain, down at Dee Why beach, I knew he was playing with the dolphins.”

Mike also shared photos and a video of dolphins jumping through waves close to shore.

Locals have hailed Mercury as a hero for alerting his friends of the shark and urging them to get out of the water.

He had only been in the water for about 30 minutes before he was attacked.

In a statement from his family after the attack, Mercury was described as “loving, devoted and ridiculously fun”.

Maria (left), Freedom (middle) and their family released a statement remembering the beloved husband and father. Credit: Supplied

“He surfed every day and loved the ocean — it was one of his greatest passions. He was also deeply connected to the surfing community, which has been so kindly supporting us and sharing in this heartbreaking loss,” the statement read.

“He was Maria’s soulmate, our best friend and the most loving father to Freedom, his daughter who he is so proud of.

“Their bond was extraordinary, and he always placed his family above everything else. His family meant the world to him.”

In Mercury’s funeral notice, his family said they will be organising a second event due to an “overwhelming response” from the community, with the time and date to be confirmed.