Which characteristic do euglenoids and algae share

Euglenoids are unicellular protists commonly found in fresh water.They don not have a cell wall, despite that, a protein rich cell membrane called pellicle is present in Euglenoids.
Whereas,Algae are eukaryotic organisms comprising of no roots, stems, or leaves but they filled with chlorophyll and other pigments to carry out the process of photosynthesis. Similar to Euglenoids, they occur most frequently in water, specifically in plankton.
Hence,
Euglenoids and algae share a common characteristic,that is both are autotrophs. They produce complex organic compounds from simple substances present in their surroundings, by the use of energy from sun-light or inorganic chemical reactions.

The higher you go up the less oxygen there is