Thank you, if I understood you correctly in the second question, algae do not explain to me because somewhere in the forest there are algae that I did not pick up?
Probably not Algae but a Feather or a Mushroom, but since they are part of the spawn pool they may spawn instead of Algae, so you have to pick them up as well to free up their spawns.
For example, if a map spawns at random a total of 6 items:
Feather - Feather - Mushroom - Feather - Algae - Algae <--- 2 Algae spawned in this case
And you collect only the Algae:
Feather - Feather - Mushroom - Feather - (Nothing) - (Nothing)
Then the next day, the first 4 items already exist, so only the last two respawn at random, and because the spawn is random, you might get:
Feather - Feather - Mushroom - Feather - Algae - Feather <--- only 1 Algae spawns in this case
or
Feather - Feather - Mushroom - Feather - Mushroom - Feather <--- NO Algae spawns in this case
or
Feather - Feather - Mushroom - Feather - Feather - Feather <--- NO Algae spawns in this case
etc...
basically only the ones you collected will respawn as "something" the rest will remain. But if you collect the Feathers, Mushrooms, etc as well, then you will get:
Feather - (Nothing) - (Nothing) - (Nothing) - (Nothing) - (Nothing) <--- for example, you missed one feather in this case.
Then the next day you might get the following spawns:
Feather - Algae - Algae - Feather - Algae - Mushroom <--- 3 Algae spawns in this case
or
Feather - Algae - Mushroom- Feather - Feather - Mushroom <--- 1 Algae spawns in this case
or
Feather - Algae - Mushroom- Feather - Feather - Algae <--- 2 Algae spawns in this case
etc...
Basically, collect mushroom, feathers and other junk as well to increase chances of Algae spawning the next day.