"Hirnstein", "Hirnstoa" = brainstone - limestone from lake "Chiemsee", surface covered with cauliflower-like lime-crust
<p>size: 17x14x8cm
</p>
locality: lake "Chiemsee", Bavaria
Hans Lauterbach <a href="//commons.wikimedia.org/wiki/User:Furchenstein" title="User:Furchenstein">Furchenstein</a>
CC BY 3.0
<span class="int-own-work" lang="en">Own work</span>