Which protists act like fungi?
Slime molds and water molds.
Protists are usually single celled eukaryotes that don't really fit in anywhere. There are plant-like protists (e.g. algae), animal-like protists (e.g. protozoa) and fungi-like protists. Their classification is based on their mode of nutrition, which is extremely diverse.
Slime molds and water molds are both included in the kingdom protista and considered fungi-like protists.
Slime molds are a diversified eukaryotic group. Generally cells form a collective mass and grow on dead and decaying organic matter.
Water molds (oomycota) are found in wet environments, preferably near fresh water sources and upper layers of moist soil. Like slime molds, they feed on decaying organic matter.