In advance: Make fondant trims. Tint fondant: 1 oz. dark rose (jellyfish); 1/4 oz. light rose (flowers); 1 1/2 oz. violet (coral), 1/8 oz. darker violet (coral spots); 1/8 oz. red (jellyfish and rock spots); 1 oz. tan (sign). For coral (standing in background), roll a 2 x 3/4 x 1/2 in. high log base. Attach 3 tapered 1/2 in. diameter spikes (one 2 in. high, two 1 1/2 in. high). Attach assorted darker spots using damp brush. For rocks, shape 3/8 in. diameter small, 5/8 in. diameter medium, 1 in. diameter large. Attach red spots to small and medium rocks. For flowers, roll out light pink 1/8 in. thick. Use medium and large blossom cutters from set to cut flowers; let dry then attach to rocks with fondant adhesive. For sign, roll out tan 1/4 in. thick. Cut 1 1/2 x 2 in. wide sign. Use knife to indent boards and cut irregular ends. Let dry 24 hours then write message with FoodWriter. Cut Lollipop Stick to 3 1/2 in. long and attach to back using fondant adhesive, leaving 1 in. extended at bottom to insert into base. Let dry. For jellyfish, roll out rose 1/8 in. thick. Cut bodies using wide end of tip 1D and 2A. Attach 1/8 in. and 1/4 in. diameter spots. Set on waxed-paper covered board. Cut seven legs for each, 1 to 1 1/4 in. long, 1/8 in. wide. Attach to bodies and arrange into curves. Let dry then attach to coral using fondant adhesive.
Prepare cereal treat mixture and press into 1 in. high layer in prepared pan; let set. Cut 3 1/2 in. squares. Spatula ice topswith buttercream. Pipe tip 2 glasses on SpongeBob topper and position on treat. Insert sign. Position rocks and coral. Use buttercream to pipe tip 2 net and tip 5 rim and handle.
* Combine Violet with Rose for violet shades shown.
* Combine Rose with a little Violet for rose shades shown.
* Combine Brown with Christmas Red for Brown shown.