Costa Rica sits along the Pan American mountain range that goes from the Andes to the Rockies to Alaska. There are lots of volcanoes, active and not. The effect can be seen on many beaches on the Pacific side, where tan to black lava flows have not yet been reduced to sand. Low tide brings interesting pools, with critters from very small, like tiny hermit crabs such as the one that unexpectedly showed up in our bedroom (https://www.facebook.com/photo/?fbid=10161256324502313&set=a.128314812312) to larger fauna, who don't seem to mind lounging on rocks.
