Seen at very low tide on Combe Martin beach, North Devon - a sheltered cove on the Bristol Channel.
Some had more "pods" - and there was a creature "nesting" or sheltering or growing inside some of the pods.
Not sure if entire thing is an animal with its own young - or with young of another - or a plant holding an animal.
these are 3 Buoy Barnacles; see, eg http://www.ispot.org.uk/node/284779 and http://www.marlin.ac.uk/speciesinformation.php?speciesID=3196 .
The yellowy bit of 'plastic' they secrete themselves in order to float. A related species is the common goose barnacle lepas anatifera,