Seeds in an eggshell progress and a question

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On February 1st, I wrote a discussion about my wife planting seeds in eggshells filled with dirt. In the photo I took then, all you see is eggshells and dirt. Now, ten days later, what we think is the arugula growing fast enough that Anne had to raise the roof over the little plants to make room. She asked me (who knows verrrry little about gardening) if I thought she should crush the egg shells once it is warm enough to put the plants in the ground. We think that the shells may be strong enough to prevent the roots from spreading in the soil. Trying this eggshell thing out came from a comment made by @LadyDuck on a post. I know she will have an opinion on our question. Does anyone else have an idea?