Learning how worms get in my pond

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Wishing Well

I wish I knew why my pond gathers worms every time it rains. There are three, four, five, or more worms wiggling in my pond, and I can't figure out how they get in it. Do they crawl across the tile and scale the 2 1/2" high, 10" wide border? Could they be falling from the sky with the rain? Any ideas?