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When the field goal is very, very nice, the denture effect becomes more pronounced, to the point that it starts to resemble a second, retractile mouth, tucked within the larger one; I think of “Alien.”

The bridge is formally known as a “retractile” bridge.

The pseudopods are retractile, the axial filament being absorbed as the filament grows shorter and thicker and disappearing when the pseudopod merges into the ectoplasm, to be reformed at the same time with the pseudopod.

Most species have sharp, curved claws, often retractile between some of the lamellae or into a special sheath.

The Carchesium differs from the common Vorticella, by branching like a tree, but the stems are all retractile, although the trunk seldom exercises the power.