Complex sentence: The female lays the eggs vertically and side by side, held together by a sticky substance excreted to coat the eggs, head end down, creating an egg raft that is convex below and concave above with ends that are typically upturned.
Split into simpler sentences: The female lays the eggs vertically and side by side, held together by a sticky substance excreted to coat the eggs. The eggs are laid head end down, creating an egg raft that is convex below and concave above with ends that are typically upturned.