*Looks at info*Shouldn't it be according the Katakana, "Soylent Base", as in Soylent Green.
Anyway, you must get the Who Knows What from the Soylent Base to make it available but it's not from an enemy drop
(the wiki only say you must get 1 Soylent Base' Who Know What and then appraise, something like that).
Instead, it's well hidden in there.
This Let's Play (which covers optional content from various scenario and thus contain
SPOILERS) show you the location :
http://www.nicovideo.jp/watch/sm6915181If you don't have an account there, use a redirector like this one :
http://www.mmcafe.com/nico.htmlStart looking from at least 12:35 up to around 13:00.
Optional boss might or might not be needed to be defeated to gain access to this place.
Really, Let's Plays can get really convenient when you need to get info from Japanese games. ^^
Also. the Octopus Board is a reference to SaGa Frontier where said item apparently give nifty bonuses to Mechs.