Shelly creatures such as trilobites and brachiopods, of whose ancestors there is little sign in the rocks, are suddenly everywhere.

像三叶虫、腕足动物此般壳类动物的祖先没有在岩层中留下什么痕迹，但它们的遗迹却突然间比比皆是。

Some creatures like trilobites and brachiopods survived though.

不过，一些生物如三叶虫和腕足动物幸存下来。

Yes, there were some mollusks and simple shelled creatures like brachiopods.

是的，有一些软体动物和简单的带壳生物，如腕足动物。

These tubes appeared only on brachiopods — never alone or on other animals.

这些管子只出现在腕足动物身上——从来没有单独出现过， 也没有出现在其他动物身上。

This suggests that the tube-dwelling creature needed the brachiopod to survive.

这表明这种管栖生物需要腕足动物才能生存。

Thousands of brachiopod fossils at the site had been clustered in sediment once covered by the sea.

该遗址的数千块腕足动物化石曾聚集在曾经被海水覆盖的沉积物中。

Plankton diversified, followed by a host of suspension feeders like certain types of brachiopods, rugose corals, and bryozoans.

浮游生物多样化，随后出现大量悬浮饲养者，如某些类型的腕足动物、皱纹珊瑚和苔藓虫。

The brachiopods were likely filter feeders.

腕足动物很可能是滤食动物。

If true, then tube-covered brachiopods would get less food.

如果属实，那么管状腕足动物将获得更少的食物。

Now, a fossil bed of brachiopods in Yunnan, China, offers strong evidence for parasites from almost 100 million years earlier.

现在，中国云南的腕足动物化石床为近 1 亿年前的寄生虫提供了强有力的证据。