I’m sure you did, but that is not a good thing. At least where I’m from, a contract is a must have. It states everything related to your job, including tasks, vacation time and salary. Without it you have fewer (or none) legs to stand on should your employer be an ass.

You wouldn’t buy a house without signing the paperwork proving it’s yours and you should not work without a signed contract.

I’m no neuroscientist so I can’t in good faith comment on our development, so I’m only arguing against the contract signing part.