[Illustration]
"Here is the photo. of an oyster-shell which has been in a tea-kettle
for seven years. When I put it in it weighed about one and a half
ounces, and was not more than three thirty-seconds of an inch thick in
any part. Now it is three-quarters of an inch thick and weighs eleven
ounces. It had lain out in the garden for a long time and lost all the
crust, which accounted for it being so thin at first. No one has ever
been able to say what it is, although many have seen it in the glass
case in the shop."--Mr. R. G. Foster, Post Office Drug Stores, High
Street, Burford, Oxon.