Monoplacophorans

The monoplacophorans (class Monoplacophora) are represented by only a handful of species of limpet-like molluscs. They were known only as fossils until the discovery of live individuals in 1952. They have now been collected, mostly from deep water, in scattered locations around the world.
Monoplacophorans are peculiar because their gills and other organs are repeated along the body, which is reminiscent of the segmentation of annelids.

Micropilina Rakiura

Internal anatomy of Micropilina