Before Spider-Man 3‘s budget soared to approximately the same budget of the entire Apollo space program (in adjusted dollars, no less), the FX crew found themselves squeezed for cash. In an attempt to create the oozy feel of the black Spidey suit taking over, they tried to take a page from the olden days of FX, where things were done in-camera as opposed to after the fact with CG. Here they try a Giant African Snail, hoping that if they can de-shell the thing, get Tobey Maguire to stand still for long enough, and then speed up the frame, they might be able to unleash a bunch of these on the actor and get an effect on the cheap.
Sadly, shortly after this test was shot, all the snails found themselves reduced to escargot on the craft services table. So the whole idea was scrapped and instead $125 quadrillion more was thrown at the FX.