There are a number algae like "algoid" organisms. These include not only DNA based organisims but GNA, TNA, and HDGTNA ones as well. These are classified as D-algoids and G-algoids, for example, depending on their genetic basis.
All algoids have a nucleus enclosed within a membrane and chloroplasts bound in one or more membranes. They lack the leaves, roots, and other organs that characterize higher plants. They are photosynthetic. While many are photoautotrophic, some are mixotrophic, deriving energy both from photosynthesis and uptake of organic carbon either by osmotrophy, myzotrophy, or phagotrophy. All algae have photosynthetic machinery, and so produce oxygen or sulpher as byproducts of photosynthesis, depending on the photosynthetic bacteria their chloroplasts derive from. Many algoids have high silica contents.
Most algoids are unicellular flagellates or amoeboid-like, but there are also colonial and non-motile forms. Some of the more common organizational levels, more than one of which may occur in the life cycle of a species, are
Colonial: small, regular groups of motile cells
Capsoid: individual non-motile cells embedded in mucilage
Coccoid: individual non-motile cells with cell walls
Palmelloid: non-motile cells embedded in mucilage
Filamentous: a string of non-motile cells connected together, sometimes branching
Parenchymatous: cells forming a thallus with partial differentiation of tissues
A few have reached even higher levels of organization, with full tissue differentiation.
Additionally, some algoids form symbiotic relationships with other organisms suppling photosynthates to the host organism providing protection to the algoid cells. The host organism derives some or all of its energy requirements from the algoids.
There are approximately 200,000 species of algoids.
Some exemplary species:
Glass Grass: Glass grass is a silvery green HDGTNA based algoid whose high silica content makes it rigid and renders the blades sharp. Glass grass colonies grow both in marine and terrestrial evirons.
Garmp: Garmp is another silica heavy algoid species. It resembles Kelp, but with an "armored" layer.
Silacin: Silacin is a silica heavy organism, similar to a lichin.