Coral-crinoid associations, where a coral overgrew a crinoid's stem, were among the very common Palaeozoic benthic associations, lasting until the end of the Palaeozoic. Many skeletal overgrowths described so far document syn vivo relationships. This type of interaction is unknown from later, Meso- and Cenozoic deposits, and to date has been unknown from recent seas. Here we analysed two individuals of the crinoid Metacrinus rotundus collected from mesophotic depths off the Japanese Pacific coast, overgrown by a single zoantharian polyp of Abyssoanthus sp. (Anthozoa: Hexacorallia: Zoantharia: Abyssoanthidae), and by some sea anemones identified as Metridioidea sp. indet. (Hexacorallia: Actiniaria). These azooxanthellate hexacorals do not possess skeletons, and were located below the host's feeding fan. Our microtomography examinations showed that the anemones did not modify the host's columnals. These specimens offer a good ecological analogue to similar associations of rugose, Cladochonus-like and tabulate corals known from the Palaeozoic. While in our specimens competition for food between hexacorals and crinoid likely does not occur, such interactions are possible. Both zoantharians and sea anemones show similar corallite/oral disc diameters to rugose corals and Cladochonus-like cnidarians that overgrew crinoids in the Palaeozoic, and therefore they probably obtained similar sizes of food particles. In environments with low relief seafloors these hexacorals benefited from their elevated position, and therefore stronger feeding currents. As both Actiniaria and Zoantharia have their phylogenetic roots deep in the Palaeozoic, and coral-crinoid associations are common among Palaeozoic tabulate and rugose corals, we speculate that also Palaeozoic non-skeletal corals, inferred from molecular studies, may have also developed this strategy of settling on crinoids, and therefore occupying similar ecological niches to these hexacorals described here. This report documents that coral-crinoid associations, characteristic of Palaeozoic benthic communities, and thought to have disappeared by the end of Permian, exist in modern seas.

珊瑚-海藻类的结合体是珊瑚在海藻类的茎上长满的地方，是很常见的古生代底栖生物体的一种，一直持续到古生代末期。迄今为止描述的许多骨骼过度生长都证明了合成体内的关系。这种相互作用的类型在后来的中，新生代沉积物中是未知的，迄今为止，在最近的海洋中还是未知的。在这里，我们分析了从日本太平洋沿岸的中生深处收集的两个海百合类圆头猴，它们被阿比索anthus的一个单一的靠日生动物的息肉所长大sp。（Anthozoa：Hexacorallia：Zoantharia：Abyssoanthidae），并被一些海葵确定为Metridioidea sp。indet。（六角珊瑚：猕猴桃）。这些偶氮杂蒽酯六聚体不具有骨架，位于宿主的饲喂风扇下方。我们的显微断层摄影检查显示，海葵没有改变宿主的柱状体。这些标本提供了很好的生态类似物，类似于古生代已知的类似皱纹，克拉德龙和列表珊瑚的组合。虽然在我们的标本中可能不会发生六种珊瑚和类海藻之间的食物竞争，但这种相互作用是可能的。zoantharian和海葵都显示出与皱纹珊瑚和Cladochonus相似的珊瑚/口盘直径样的刺胞动物在古生代长满了海百合，因此他们可能获得了相似大小的食物颗粒。在低浮雕海底环境中，这些六珊瑚受益于其较高的位置，因此馈电电流更强。由于Actiniaria和Zoantharia都在古生代中有较深的系统发育根源，并且古生代表珊瑚和皱纹珊瑚中珊瑚-古龙水族很常见，因此我们推测，根据分子研究推断，古生代非骨骼珊瑚也可能已经发展了这种策略。定居在海百合上，因此占据了与此处描述的这些六珊瑚相似的生态位。该报告记录了古生代底栖生物群落特有的珊瑚-海藻类生物联系，并认为在二叠纪末期已消失，