Aeolidioidea is a superfamily of small sea slug

Slug

Slug is a common name that is normally applied to any gastropod mollusc that lacks a shell, has a very reduced shell, or has a small internal shell...

s, the aeolid nudibranch

Nudibranch

A nudibranch is a member of what is now a taxonomic clade, and what was previously a suborder, of soft-bodied, marine gastropod mollusks which shed their shell after their larval stage. They are noted for their often extraordinary colors and striking forms...

s. They are gastropod mollusks.

2005 taxonomy

The superfamily Aeolidioidea consists of the following four families (according to the taxonomy of the Gastropoda by Bouchet & Rocroi, 2005

Taxonomy of the Gastropoda (Bouchet & Rocroi, 2005)

The taxonomy of the Gastropoda as it was revised by Philippe Bouchet and Jean-Pierre Rocroi is currently the most up-to-date overall system for classifying gastropod mollusks...

):

• Aeolidiidae
  Aeolidiidae
  Aeolidiidae, the aeolid nudibranchs, are a family of Nudibranchs. Many feed on hydroids and thus have highly serrated radular teeth.- Genera :Genera and species within the Aeolidiidae include:* Aeolidia Cuvier, 1797 - type genus...
  
   Gray, 1827
• Facelinidae
  Facelinidae
  Facelinidae is a taxonomic family of colorful sea slugs. These are specifically aeolid nudibranchs. They are marine gastropod molluscs.- 2005 taxonomy :...
  
   Bergh, 1889
• Glaucidae
  Glaucidae
  Glaucidae is a taxonomic family of colorful sea slugs. These are specifically aeolid nudibranchs. They are marine gastropod molluscs in the superfamily Aeolidioidea.-Genera and species:Genera and species within the family Glaucidae include:...
  
   Gray, 1827
• Piseinotecidae
  Piseinotecidae
  Piseinotecidae is a taxonomic family of colorful sea slugs. These are specifically aolid nudibranchs. They are marine gastropod molluscs.-Genera and species:Genera and species within the family Piseinotecidae include:* Piseinotecus E. R. Marcus, 1955...
  
   Edmunds, 1970

Synonyms of families within this superfamily include:

• Caloriidae (synonym of the subfamily Facelininae)
• Cratenidae (synonym of the subfamily Crateninae)
• Herviellidae (synonym of the subfamily Herviellinae)
• Myrrhinidae (synonym of the subfamily Favorininae)
• Phidianidae (synonym of the subfamily Facelininae)
• Pleurolidiidae (synonym of Aeolidiidae)
• Pteraeolidiidae (synonym of the subfamily Pteraeolidiinae)
• Spurillidae (synonym of Aeolidiidae)

2007 taxonomy

Gosliner et al. (2007) have elevated subfamily Babakininae (that was within Facelinidae) to the family level Babakinidae.