When Sue Perry revised her health care directive about five years ago, her sister Katy was shocked by one detail.

Sue, who had been diagnosed with a form of brain cancer and had moved to Minneapolis from New York to live with her sister, wanted her ashes to become part of a coral reef.

"I said, 'Sue, you want to do what?'" Katy recalled. "It just sounded kind of crazy to me."

What Sue wanted was to have her cremated remains turned into a "reef ball," a craggy mix of concrete and ashes that divers place on the ocean floor. The reef balls act as a habitat for sea life, helping to regenerate deteriorating coral reefs.

"Imagine a bowling ball, only the finger slots go all the way through," said Steve Willwerscheid, who has had his share of unusual requests at Willwerscheid Funeral Home and Cremation Center's natural burial division in West. St. Paul.

Ecologically friendly and highly individualized burial alternatives are a growing niche in the funeral industry, and a popular choice for environmentally conscious baby boomers who seek to have ashes planted with trees or bodies buried in biodegradable wrappings.

Willwerscheid gets asked all the time about alternatives to traditional burial. Many people will ask about putting cremated remains inside a bulb of a plant, or to save them in a piece of jewelry. Some clients have inquired about making a kind of smoky diamond by compacting cremains under high pressure. But no one, yet, has asked him for a reef ball.

"Obviously we don't do a lot of that up here," he said. "We're a little far from the ocean."

But we're not without water.

Here, the scattering of cremated remains on public land, including Minnesota's lakes, is prohibited by litter laws. "However, I've been doing this 33 years, and I've never heard of anyone getting arrested or ticketed for doing it," Willwerscheid said.

Sue Perry loved sailing and being near the ocean, and had been intrigued by becoming part of something that was living after she died, her sister said.

"She is part of the ecosystem," Katy said.

For her reef ball, Perry turned to Eternal Reefs in Sarasota, Fla. Their reef balls weigh between 650 and 4,000 pounds and are clustered together to create a larger artificial reef. While they have reef ball sites all along the East Coast, the largest is off Lido Beach near Sarasota, where 600 reef balls have been dedicated.

Perry died in January 2016 at 66, and in June, her siblings flew with her ashes to Florida. It cost about $4,000 for a long-weekend that began with the casting of the concrete ball. Family members can add personal touches, and Sue's family carved the initials of her many beloved nieces and nephews and adorned the ball with shells and beads.

Next was a memorial service, and finally, the boat ride out into the Gulf of Mexico. Several families rode together and watched as the balls were lowered from a barge and placed by divers into their new underwater home.

"We felt like we were on a little odyssey," Katy said. "It was really cool, despite my own skepticism."