Reference for Chullin 252:28

עכבר שחציו בשר וחציו אדמה הנוגע בבשר טמא באדמה טהור

IF IT WAS PIERCED, HOWEVER SMALL THE HOLE WAS, IT IS UNCLEAN.<span class="x" onmousemove="('comment',' And contact with the shell would render the person unclean, for in this case the shell serves as a protection to foodstuff and as such conveys uncleanness.');">¹⁵</span>

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