What is the plug 2-3" behind the oil drain plug? Help please

[Chico06GZ250]

Hi everyone,

I did the first oil change on my gf's 2006 GZ250 on Sunday. I removed the oil drain plug first, only a bit came out since it appeared to be low on oil. Thinking it may have a second plug, I also removed the plug that sits 2-3" to the rear of the motor behind the oil drain plug. It is the same size and color as the oil drain plug.

When this was removed, a spring and what looked like a magnet fell out. I put it back together how I thought it came out (smaller piece inside the spring, then back into the motor with the smaller piece touching the plug and the extended spring pointing upward). I tightened the plug along with the drain plug, replaced the oil filter, filled it with oil and started it up.

It seems to run fine, but I want to know what purpose that other plug/spring setup serves. I did a search and this question has been asked several times but never answered, I can't find anything about it in either the owner's or service manual either. Can someone please let me know?

Thanks in advance