Algae can be used for fast and effective taming of herbivore/omnivore creatures. Algae is 4× faster taming than Crops and a much higher taming effectiveness that's pretty close to Kibble.

Taming effectiveness comparison of a level 150 Trike (at 1× taming):

Kibble: 99.8%

Algae: 98.8% 🌿

Crops: 83.3%

Mejoberries: 73.8%

Berries: 55.6%

Uh, so.. People can absolutely steal algae from ur tamed archelons, even if it's PvE, so, do with that what you will

To get Archelon Algae, you need to tame an Archelon, which will passively produce the algae over time.