Harry had been held back in Potions, where Snape had made him stay behind to scrape tubeworms off the desks.
哈利在魔药课上被留了堂，斯内普叫他留下来擦去桌上的多毛虫。
英语百科
Tube worm
（重定向自Tubeworm）
A tube worm is any worm-like sessile invertebrate that anchors its tail to an underwater surface and secretes around its body a mineral tube, into which it can withdraw its entire body.