Seaman

Unlimited food:
You need two VMU's to preform this trick. Begin a new game, then
use your second VMU to save. Connect this 2nd VMU to a VMU that
has an ongoing game. Transfer the food from the new game
to the ongoing game. Repeat as many times you want.

Quick evolve
Faster evolution:
Modify the Dreamcast's system date ahead several days
for quick evolve.

Hypnotize Seaman
Move the Analog-stick in circles around Seaman's head.

Move rocks
Press X + R and press Left or Right

Secret audio message:
If you insert your game disc into an audio CD player you can listen
hidden message.