Definition of water-blob in US English:

water-blob

noun

English Regional
  • Marsh marigold, Caltha palustris (also called horse-blob, mareblob, May-blob); (also) the rounded flower of this or of any of several other aquatic or moisture-loving plants.

Origin

Early 19th century; earliest use found in John Clare (1793–1864), poet, farm labourer, and naturalist.