Labyrinthulomycetes (ICNafp) or Labyrinthulea[2] (ICZN) is a class of protists that produce a network of filaments or tubes,[3] which serve as tracks for the cells to glide along and absorb nutrients for them.

The cells are uninucleated and typically ovoid, and move back and forth along the amorphous network at speeds varying from 5-150 μm per minute.

[3] Within Bigyra, the labyrinthulomycetes are the sister group to Eogyrea, a class containing the species Pseudophyllomitus vesiculosus and the environmental clade called MAST-4.

The structure of their zoospores and genetic studies show them to be a primitive group of heterokonts, but their classification and treatment remains somewhat unsettled.

This class usually contained two orders, Labyrinthulales and Thraustochytriales (ICBN), or Labyrinthulida and Thraustochytrida (ICZN), but a different classification has recently been proposed.