Weird corrosion in boot

[adyRE]

just noticed this weird corrosion in the boot around the strap down points... No idea what's causing it.

 

[NHN]

Water damage maybe, kinda also looks like an old battery leak.

Clean the hoover out, then hoover it up, brush the area & inspect in the house then inspect the clean area in the car.

 

[quattrogone]

Looks like some sort of dead alien thing in the 2nd pic, that's certainly a weird mess

 

[g00se]

Looks like something has been eating/p00ping and nesting in there?!?