It lives only here, 它只生活在

252. This mysterious creature
     这个神秘的生物
253. hardly ever appears on the surface of the dunes.
     鲜少出现在沙丘表面
254. But there are signs on the sand that can give it away.
     但沙子的移动 却泄露了它的行踪
255. It lives only here,
     它只生活在
256. where the sand grains are so perfectly dry and polished,
     沙粒干燥光滑的地区
257. that they flow almost like water.
     让它们可以如流水般行动自如
258. It's no bigger than a ping-pong ball.
     它的体型还没有乒乓球大

来自《行星地球 第二季 第四集 Planet Earth S02E04 沙漠》第 255 行