...This is a lot more interesting than those other options.
On a strip of sandy beach, on the edge of huge lake, you discover a huge, spiraled sea-shell, nearly twenty feet tall. As if that wasn't odd enough, there also appear to be windows and a chimney built into the shell. There is even a small trail of smoke curling up from the chimney... somebody is home.
What kind of person would make their home inside a giant seashell? Well... I guess you could go knock. Maybe they're friendly. Maybe they're cute. Heck, they're probably waiting to greet you with a warm hand-knitted scarf and a mug of hot-chocolate! How can you resist such hospitality?
...So... go knock?