Exchange tokens are amongst the more obvious securities IMO. I think they tick all marks of the Howey Test:

    - An investment of money
        (Send money/BTC, get token)
    - In a common enterprise 
        (the exchange)
    - With the expectation of profit
        (Token burns)
    - To be derived from the efforts of others
        (Exchange pays with profits for token burns)

https://www.investopedia.com/terms/h/howey-test.asp