Answer:
I am a creature with a “tight” name.
I'm as simple as a circle worthless as a leader; but when I follow a group their strength increases tenfold. By myself I'm practically nothing.
You may enter, but you may not come in. I have space, but no room, I have keys, but open no lock. What am I?
I go in dry and come out wet. The longer I stay in the stronger my surroundings get.
Soft, hairy, from door to door. I am the pet that always stays on the floor. What am I?
No matter how little or how much you use me, you change me every month.
What am I?
Animal
Difficult
Easy
Food
Funny
Kids
Logic