This is a fully automated sea pickle farm! I am aware that this is a largely useless piece of redstone engineering, but I had lots of fun tinkering around with it. Here's a breakdown of how it works:

• Top layer - anonpmc2558251's amazing auto-melon farm produces melon slices which are collected into a hopper.
• Second layer - The melon slices are put into a composter, from which the bone meal is transferred downwards into the dispenser by a group of hoppers (and a minecart with hopper). There also is a redstone clock on this level, which activates the dispenser if a bone meal is inside.
• Third layer - This layer is where the sea pickles are grown. When bone-mealed, sea pickles can produce "offspring" on adjacent coral blocks. The dispenser bone-meals the sea pickles in the center, which then causes more sea pickles to grow on the 12 other coral blocks. If a sea pickle grows on one of the outer corners of this square of coral blocks, an observer will relay a redstone pulse downwards to a mechanism (this mechanism is basically another layer, in between layers four and five) which causes four pistons to contract and push upwards again. This is how the sea pickles are broken.
• The fourth layer (which, confusingly, is actually above the third layer) - This bit consists of water. The dropped sea pickles will float upwards in the water, and, once they reach the surface, get carried with the flow. The water takes the sea pickles to the very edge of the build, where the water flows downwards, taking the sea pickles with it.
• The fifth and final layer - The sea pickles have "swum" all around the entire contraption steering the pistons, and on this layer, they are pushed to a central point again, where a hopper picks them up and transports them into a chest. Done!

This farm produces around 1.5 sea pickles per minute, so it's not massively efficient, but hey, it works!
Again, all credits for the melon farm on the top layer go to anonpmc2558251! Thanks for that piece of engineering!
Have fun with my farm, but please don't use it for commercial purposes or claim it as your own work.