Giant spear

Spears are objects that stretch up and down, in an attempt to hurt Sonic. The spears have also been used as a weapon in Sonic Heroes and Shadow the Hedgehog.

Sonic the Hedgehog (16-bit)
The spears appear in the underwater segments of Labyrinth Zone, often appearing in narrow passageways, where the underwater physics can make dodging them difficult. They also line the walls of the boss chamber, attempting to slow Sonic down.

Sonic the Hedgehog 2 (16-bit)
They appeared in Metropolis Zone where they are inside of a box. They continually pop out of different sides, and are often found in large numbers, forcing the player to carefully time their jumps to avoid them.

Sonic 3D Blast
They appeared in Spring Stadium Zone, the spears were used to block Sonic's way when you must collect Flickys and place them in the Giant ring to lower them. There are also little holes on the ground with spears in them that will rise up and damage Sonic if he steps on one.

Sonic Heroes
The spears were used as weapons wielded by Egg Pawns.

Shadow the Hedgehog
The spears appear again as weapons wielded by Egg Pawns.

Sonic and the Secret Rings
The spears appears as objects that are shot straight at you in Sand Oasis.

Sonic Unleashed (Wii/PS2)
Once again, spears are thrown at the player from an unknown source in an attempt to hit Sonic while he is running along a narrow, curving pathway during Dragon Road.

Sonic the Hedgehog 4 Episode 1
The spears again appear in Lost Labyrinth Zone, where they serve the same purpose that they did in Sonic the Hedgehog (1991).

Adventures of Sonic the Hedgehog
In an Adventures of Sonic the Hedgehog episode called "Sonic Breakout", the spears are used in a spear shooter, although the color of the spears are red instead of white. It also appeared in "Sonic Gets Thrashed", were it was use as a harpoon, although the spear color was white like in the first game.