Stephen Price lifts the lid off a small plastic container filled with what looks like dark, rich coffee grounds.
The earthy scent escapes as he buries his finger deep inside and lets the kids around him in on a little secret.
"Each one of those is a little worm doodle," he said.
"Ewww," a collective chorus escapes from suddenly grimacing faces, many of whom revolt at the idea of touching worm castings, or manure.
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But Price is quick to defend.
"Your little grubby hands have more bad bacteria on it than my castings have in them."
Price, 52, has worked with worms for the last 30 years.
The first kind wiggled through computer systems as viruses, spreading infection and paralyzing hard drives. He invested more than 25 years fighting the virtual creatures.
The second, red wigglers, he holds dear.
Despite living in the soil, they are anything but dirty to the professional vermicomposter.
Vermicomposting - using worms to turn kitchen scraps and other trash into nutrient-rich worm castings - has become a growing part of the green movement.
The benefits are two-fold. The worms eat the waste, and then turn it into manure that can be used as fertilizer to grow better gardens and flowers.
Price has been in the business for four years, a venture he began at first for his own benefit to maintain a more organic garden.
Now he visits libraries, farmer's markets, and flower shows, teaching folks the simplicity of vermicomposting.
"Make it yourself. Keep it local," he says. "That reduces energy, your overall footprint."
He'll set anyone up with worms and a bin, and explain what to feed them.
Eggshells, coffee grinds, tea bags, kitchen scraps, even shredded confidential documents.
"Your old salad that went bad in the bag. Dump that in there," he said.
He knows one lady who keeps her vermicompost under the kitchen sink, like a living garbage disposal.
Take the castings and spread them on your plants, Price tells the curious.
"You are concentrating the nutrients," he said. "If you want to perk a plant up quick, spray a good fertilizer on its leaves."
Worm castings have become a growing business as people look to rely less on chemicals for their gardens.
"We're getting a good bit of interest from small home gardeners who want to grow a nice tasty vegetable."
Price keeps around 8,000 worms in his basement, and will sell castings to anyone from the gardener with a small patch, to the farmer who needs enough to fertilize hundreds of acres of crops. He uses a distributor who specializes in worm manure.
"Gimme a week and I can have a tractor-trailer load."
And on occasion, he'll pick up an early morning phone call from a fisherman.
"You sell worms?"
"Yes, I have worms," he admits without hesitation.
He pulls out his scale and plops a handful of red wigglers down like he's weighing a pound of grapes, and meets them at the door of his home on Palaside Drive N.E., Concord..
Like his days as a computer programmer, he still comes across a bad worm. Like the tomato hornworm he found munching on his heirlooms this year.
Ever the recycler, Price nipped the issue like one would expect.
"I broke the leaf off and put it in the bird feeder," he said. "That takes care of that problem."