Help with strange SMD device ID

[AE7OO]

Greetings,

I was doing some part scrounging from some old hard drives I had and ran across the devices in the PulledChip and BoardedChip pictures.  I'm not really sure what to make of them.  They are fairly large(MMref picture has a mm scale); Looks like they are about 4mm long. The first three pictures show the device in question(The 4th one has markings identical with the BoardedChip).  The 4th picture shows the circuit one of them came out of.

I've tried looking it up under just about every combination of markings I could imagine, no luck there.  And metering it told me nothing, which considering I really only have low end meters(I tried both with a Multimeter(Centech 61593) and LCR meter(HoldPeak HP-4070L)) does not really mean much.

I want to half way say crystal because of the guard circuit (and the above metering) as seen in the Circuit picture, but there are other devices that require the same treatment. 
Plus considering the following info, I would have to say no:
- in all cases they were located away from any device
- there were already crystals/osc in use(an example is in the WithOsc picture)
- I've never seen anything like it in 30+ years.  I will admit however this is the first time I really paid attention to devices located on HD boards.
- In all cases they did not have a board reference of either X or Y.  E2, SK1, V and VR2 were how they were referred to(I could not find E1 or VR1); So I'm thinking they are not very common as there is no standard reference.

Maybe a voltage reference? 

(Also can anyone help me interpret the resister in the last picture with the blue marking.  I don't know if I should treat it as 205 or 2.5(I've already run across a resister marked with 1.0 so it might be 2.5))

4 out of the 5 logic boards I pulled had this device.

[Buriedcode]

I believe the silver/white device to be a shock sensor.  These are used to detect falling, or sudden shocks so the drive can retract the heads to a safer place to reduce potential damage from the sudden shock when it hits the floor.

https://www.murata.com/en-eu/products/sensor/shock
https://en.wikipedia.org/wiki/Active_hard-drive_protection

[AE7OO]

Thank you!! 

That tells me why I've never seen one before!  I thought my memory was going.

I've worked on various types of RF equipment, computers, and POS scanning systems.  None of which had a shock sensor like this...

[Buriedcode]

Yeah they're pretty nifty.  I believe it is to stop the heads crashing into the platters, so whilst the fall/drop/shock/hit may permanently damage the heads - the platter(s) remain intact so techs can replace the heads and extract the data.  So damage limitation, rather than prevention.