The gecko was wall-crawling quietly along the painted surface.

wall-crawling 是由名词 wall（墙）和动词 crawl（爬行）组成的复合动词，加上-ing 变为现在分词形式。字面意思是"在墙上爬行"，用来描述壁虎等动物在垂直表面移动的行为。