Darwin did extensive work on barnacles, and wrote to his cousin WD Fox in 1852:
I am at work on the second vol. of the Cirripedia, of which creatures I am wonderfully tired: I hate a Barnacle as no man ever did before, not even a Sailor in a slow-sailing ship.
But in 1855, he felt nostalgia for them, and wrote to Fox:
all nature is perverse & will not do as I wish it, & just at present I wish I had the old Barnacles to work at & nothing new
Also check out his slightly more deranged second channel, NileBlue. I love his videos because they really show the whole scientific process, errors and all