Identification of rare (?) pieces
1 is a pin used to hold train track pieces together during shipping. It can be discarded but some people find uses for it since it fits in a. minifig's hands.

Many of the others are official Lego as can be seen by the brand name printed on them. On the large pieces you should be able to see an ID number printed underneath which will help you out. I'll work through identifying some of the others.

3: Bionicle Gear 8 Tooth with Rhotuka Spinner Rod 2.5L

4: Appendage Spiky / Bionicle Spine / Seaweed / Plant Vine

5: Modified 2x2 Racing Driver, no head

6: Bar 1L with Top Stud and 2 Side Studs (credit to Victorious Victini)

7: Train Coupling New

8: Bionicle 2x3 Axle Connector with Tooth

9: Hinge Brick 1 x 2 Locking with 1 Finger Top

12: Leg Skeleton with Black Square Foot

13: Bar 1 x 8 with Brick 1 x 2 Curved Top End (most likely this newer version, but there are some older ones as well) (credit to Victorious Victini)

14: Fairing, 1x2 Stepped with Two Pins

15: Batwing

16: Modified 1x4 with Angled Tubes

17: Not Lego

18: Fire hose nozzle

19: Bionicle Weapon Cordak Ammo

20: Road Sign Clip-on 2 x 2 Square with Curved Blue Lines and Small Black Squares Pattern

21: Bat-a-rang

22: LEGO Minifig, Weapon Bladed Claw (mostly from Wolverine)

23: Horn Large

24: Minifig, Utensil Space Scanner Tool. (credit to Rin Rio-Oki)