blastoids

例句：

1. 1.The blastoids were found in the ocean depths.
   这些无脊椎动物被发现在海洋深处。
2. 2. The jellyfish is a common sight in tropical waters.
   这种水母是热带水域的常见景象。
3. 3.Hydrozoans are fascinating creatures that can change color and shape.
   水母是一种迷人的生物，它们可以改变颜色和形状。