div class=ts-pagebutton class=gotoPage data-page=1Page 1button div class=ts-imageimg data-url=the-form-of-pebbleshtmlpage=1 data-page=1 class=ts-thumb lazyload alt=Page 1: The form of pebbles loading=lazy src=data:imagegifbase64iVBORw0KGgoAAAANSUhEUgAAAAIAAAACCAQAAADYv8WvAAAAD0lEQVR42mP8X8AwAgiABKBAv+vAXklAAAAAElFTkSuQmCC data-src=https:reader035vdocumentsmxreader035viewer2022080107575068811a28ab0f07b07865html5thumbnails1jpg width=140 height=200 divp© 1990 Nature Publishing Grouppdiv