One of the Hawk moth caterpillars.

I thought it may be one of the Hawk Moth caterpillars too :o)) Just found the Name of it....
"Elephant hawk moth caterpillar".....
(Deilephila elpenor caterpillar)

Those scary faux eyes keep the hawk moth generations going.

the webbing is the protective silk it spins around itself before it produces its cocoon.
I found one in my greenhouse last year when I was sweeping up. I removed the webbing as I also thought it was spider silk. I kept the pupae in damp compost and it did hatch successfully in July.

it is an elephant hawk moth.
if you can put it back it will continue to go into the pupation sequence.

Oh! Ooo! Errrr! And there's me thinking I was doing a "Good Deed" one Lives & Learns doesn't one, I do hope it will be ok :o)), I put it in the flower bed.

if you can find it again and put it somewhere less 'open', bottom of a hedge for instance that would be better for it.